This guide was written in response to MANY MANY repeated posts by players complaining about the performance of Space Engineers on their Alienware/Gaming Grade PCs. I am frankly sick of people blaming the game without cause.

You may ask what my qualifications are here -

• I run a PC repair shop, below are many of the tricks we use to speed up old computers.
  
• I play space engineers every chance I get (over 1500 hours at this point)
  
• I mod space engineers, I currently maintain two modestly popular mods, and numerous misc map and ship submissions.
  
• I write fan fiction themed on my space engineers games
  
• I run a dedicated server for space engineers, for nearly 2+ years, based on the story of my fan fiction
  
• I make occaisional space engineers videos, usually about my mod or my fan fiction, or my server or all of the above.
  
• I report every bug I find in space engineers,
  
• I participate in some of the keen staff live streams,
  
• I have space engineers installed on 6 very different hardware computers anywhere I live or work
  
• I in-home-stream space engineers in steam to 2 more PCs.

I am also obsessed with this game. Need I say more?

Moving on -
None of my PCs are anywhere near Alienware specs, they all play space engineers well enough to do whatever task I may be doing that time.

What sort of hardware have you tested with space engineers?

• I have an older AMD 64 dual core XP PC with only 4 GB of RAM, and a nvidia GT240 (now a GT430) video card. Also the same machine running windows 7x64
  
• I have a PC on loan running keen-dev spec hardware - i5, GTX970, 16gb ram. 7kRPM HD.
  
• I also have a junky i7 2.0GHZ 8GB with a nvidia GT650 video card; this is the most used PC
  
• I also have an AMD black multicore PC i built for my daughter, running a 4way Velociraptor RAID and a GT640.
  
• I have a clunky old Dell i7 laptop with "steam os" and hybrid intel/GT650M hardware which I have been testing lately.
  
• I have an ancient Vista ASUS centrino duo PC with some old Intel chipset that I do most of my programming on, and to which I in-home stream the game regularly to test mods.
  
• I have even tried playing on a 7800GT based pc, with every tweak it was just playable. But very ugly.

The older AMD PC does struggle a bit on larger maps; the ASUS laptop even runs the game natively, at a horrible frame rate. But so far the i7 has not had an issue on any map, and the AMD64 works fine on smaller worlds too.

Thus given all the various scenarios I have tested, I can only conclude - the people making posts about "the game running badly" either have not configured their PC correctly, are lying about its specs, or are just trying to cause bad publicity.

Although I cannot do much about the publicity or the specs, I can try to teach as much as possible about configuring it.

Hopefully this guide helps someone to make the game "playable" . :o)

Note: The next few lines are somewhat trollish sounding. Included mainly for humor value.
Working in a PC repair shop, The typical owner of a high end gaming system i see, relies on the extra frame rates; high end internet connections and lower pings to compensate for poor reflexes. Why is it I only see this sort of guy? Probably cause the ones with high end systems that i dont see, know how to fix it themself - and are too busy playing games to complain on forums!

You know the type of guy; you log on a server.. you may have 100, 200 or 500 ping, he has 3 ping. He is usually in the top 10 scoreboard.. and bragging like a donkey.

Then you score against him. He is not happy. Blames it on a fluke, lag or luck. Then he singles you out for payback. Then you score against him again. Then he starts accusing you of cheating, or complains to the game host to get you kicked for "lagging the game" - most of the other players have no trouble with lag, and a few even score against you.. at some point either you or he leaves the game; willingly or otherwise.

Anyway you get the idea. * end of trollish humor *

In a nutshell if you have a good pc and this game struggles, you are doing it wrong.
Read on my friend, read on.

Before we start - make sure your PC specs fall within one of the following categories - this guide can help a little, but there comes a point where all the tweaks in the world wont be enough. Space engineers has come a long way since I first wrote this guide (Original release was only 400mb!) but it has become quite big after all the things they have added and improved on. (8gb!)

If you fall below these system requirements don't be expecting too much of your PC. Most of these tweaks certainly wont hurt it, but the amount of gain you get may still fall below the "playable" level for the game.

Which version is right for you?
To cater for the best all round compatability with older hardware, Keen Software currently maintains two official Space Engineers builds:

• "Retail" Normal Public Release, which will be 64bit Directx 11 only
  
• "Legacy" Old Multiplayer Release, which will support 32bit and 64bit Directx 9

To select your desired version:
1: Go into your steam Library list and locate Space engineers
2: Right click game in steam library, and choose properties
3: Go to the "BETAS" tab and select "dx9 32bit" for the legacy build OR "NONE" to use the normal retail build.

Build: Legacy build only
OS: Vista 32 or 64 bit. (32 for legacy build only)
CPU: At least an Intel dual core 2.4Ghz or AMD equivalent (eg 4000+)
Video: Intel Express 4000/ Nvidia GT7800+ or GT250+ with 1gb+ video memory.
Supporting Standards: At least Directx9 for 32 bit legacy, 10+ for 64bit
Ram: At least 4GB Ram. (3Gb if you play empty world)
Harddisk: 8gb free to install.

What to expect:

• Terrible to tolerable frame rates 5-25 on low quality depending on video card
  
• Harsh looking graphics on Low.
  
• Very Long world load times (10 minutes+)
  
• Only small worlds (5km) with 2 or 3 asteroids should be used.
  
• Should be able to design small ships or small asteroid bases in creative mode
  
• Basic survival (spawn in a ship, land on a roid, build a small base)

Multiplayer: Not advised.

Build: Normal Public Release or Legacy Build
OS: WIndows 7/Vista 64 Bit
CPU: i3, i5, i7 or equivalent AMD. Two or more cores.
Video: GT440/GTX550/GT640 / AMD equivalent with at least 1GB video memory
Supporting Standards: Directx 9 or Directx 11.
Ram: At least 4GB
Harddisk: 8gb free to install. 5krpm+

What to expect:

• Frame rates between 20 and 45 depending on video card
  
• Acceptible looking Low-Medium Graphics
  
• Modest World load times (4 minutes+)
  
• Should run any size world up to 50kms just fine, maybe more.
  
• Should be able to play any mode Survival or Creative fine

Multiplayer: Should work fine as client.

Build: Normal Steam Public Release
OS: Windows 7 64bit or above
CPU: i5, i7 or AMD equivalent. 4 or more cores/threads.
Video: GTX460, GTX570, GT650, GTX780,GT1050 / AMD equivalent or better. With at least 1-2GB video memory.
Supporting Standards: Directx 11+
Ram: At least 8GB DDR3+
Harddisk: 8gb free to install. 7k RPM+ or RAID

What to expect:

• Frame rates between 35 and 60 depending on video card
  
• Acceptible looking Medium-High Graphics
  
• Modest World load times (2 minutes+)
  
• Should run any size world fine.
  
• Should be able to play any mode Survival or Creative fine

Multiplayer: Should work fine as host or client.

Build: Normal Steam Public Release
OS: Windows 7 64bit or above
CPU: i5, i7 or AMD equivalent. 6 or more cores/threads.
Video: GT590, GTX680, GT780, GT970+, GT1060 / AMD equivalent or better. with at least 2GB+ Video memory
Supporting Standards: Directx 11+
Ram: At least 16GB DDR3+
Harddisk: 8gb+ free to install. 7k - 10K RPM, RAID or SSD

What to expect:

• Frame rates between 60 and 120 depending on video card
  
• Acceptible looking High Graphics
  
• Modest World load times (1 minutes+)
  
• Should run any size world fine.
  
• Should be able to play any mode Survival or Creative fine

Multiplayer: Should work fine as host or client.

Space engineers is very sensitive to several factors with regard to performance.

As of writiing there was a few things that impact both physics(sim speed) lag and frame rate -


1: asteroid showers, particularly armageddon mode seem to require a lot of calculations, especially if you are watching them; the visuals make your video card work hard, and the motion itself makes your cpu work too.



2: the "ghost block" when placing blocks can causes the game to go slightly "slow motion" Since the addition of "projectors" this issue is essentially resolved. The slowdown effect is minor to non-existent.



3: plasma effects - when looking directly into rockets it can cause a slight frame drop. Not to mention burn your face! (joke)




4: Projectors - seem to behave like the old ghost block issue above; causes a minor frame rate drop and a few quirks. Be sure to turn them off when not using them.

5: Grid Sectors Mapping/Chunks/Instancing - Partially implemented - Mainly improves performance on Dedicated servers, players only ever get sent 1-4MB of the map client side as they enter that area of the map. When playing offline/single player, the entire map is still loaded, so you get the issue that anything anywhere in the map effects you and your sim speeds.

6: Netcode: Keen has made significant changes to "netcode". Everyone should be seeing client side frame rate/sim speed gains across the board now. They recently tweaked mod loading which should see an improvement there as well.

7: Memory Leak: Important 19/3/16 The game as of this moment has an issue with releasing memory. Although usually not serious, it is recommened that you exit the game entirely between maps or servers otherwise you will see client side "sim speed" impact.

8: Windows 7 - Recent (as of 19/3/2016) windows update. There is a windows update that causes svchost.exe to use over 1 GB of ram, and a lot of CPU after installing. "Stop" the windows update service prior to playing as a work around.

When playing this game consider the capabilities of your PC
Available memory: The amount of ram combined with the number and complexity of objects in your game can have a big effect. Too many cause what I calling "physics lag" (or low "sim speed") with all the processing being performed. (The game makers themself have pointed out a number of times that the world of space engineers is really only limited by your available memory.)

Basically when you have this type of lag, you may still have a good frame rate (everything moves smooth on screen, looks nice) but when you try to walk or run, or use the tools or weapons, or fly the ships, everything seems very "slow motion" In extreme cases loading worlds may give you unable to add object or memory errors too.
(Tip: shift-f11 at any time shows frame rate in space engineers, and Ctrl-H shows a smaller graph read out)

If this happens either remove a bunch of items, or cut/paste your builds to a map with less asteroids. Some have also suggested editing your saves to remove excess objects too, SE Toolbox by MidSpace allows you to do this. The game also has a built in admin tool called "Space Master" accessed with ALT-F10. which can remove junk. You could also try to unload any unnecessary background processes to free up RAM. Refer to later guide sections for this.

CPU and GPU performance: - if your hardware is not keeping up it will cause 'ye olde' frame rate lag. When your frame rate drops, the game is very jerky - if you have enough ram, everything will be moving at about the right speed; but the picture on screen will be jumping a lot. In this situation you will need to refer to later guide sections on tweaking your video card and so forth.

The game has some performance settings as well - there is not really a whole lot of them - but there is several of note:
1: Video Mode - this should be set to a mode appropriate to both your monitor and your video card. Most Budget and mid range cards are optimal at 1024x768 although slightly increasing or decreasing this shouldn't hurt much, particularly with the mid range cards; on wider screen monitors.

2: Render Quality - this varies from Extreme to Normal. Most of the time Normal should be fine. As the game scales down visual detail somewhat based on hardware load. This section is mainly replaced by the Graphics Section now, and is probably removed on most versions of space engineers.

Under Map Options you also have the following:
3: Players - the number of players effects how many resources are needed to be allocated for a map in order to track movement inventory etc. If this is not a multiplayer server, set this to 1, and set your map to offline for the fastest experience.

4: Objects - the number of free floating materials - eg ore, components etc that are allowed before it "cleans up" the excess. obviously more means keeping track of more items and more memory and cpu. As far as performance, less is better but too small and the game might be difficult. Too many objects can effect the above mentioned "physics lag" quite a lot.

5: Environment - Anything more than safe requires much more processing as it needs to keep track of various random meteor showers, at the armageddon setting there is also quite a lot of graphical processing. Best performance is at "safe"

6: Auto save - if you leave this off, you wont be interrupted periodically while you wait for the map to save. But remember to save manually. The game can still crash sometimes.

7: Cargo ships - If you enable these, it exponentially increases the size of your map, as they spawn randomly at 10k or so away. If you hijack a few that increases your object count rapidly.

8: Thruster damage - this might not be obvious - but when thruster damage is on it causes extra calculations when you fly near other objects, as they will deform if in front of a rocket. This means landing could cause brief slowdowns.

9: Various options - several extra options exist now, such as enabling or disabling weapons, drones, encounters, cargo ships, various creatures, pirates etc. These all require extra resources, so disabling them is obviously the fastest option. But consider carefully, these also effect how fun the game is!

10: Advanced: Mods - This allows you to add scripts or custom skins, backgrounds, blocks or objects/ores - some mods can really eat up resources, if a particular mod'd save struggles, switch to play offline and creative mode to enable debug mode - this should give more detail when you load it. There is also some hotkeys for spectator and debug mode if you need to examine in detail.

Also when creating new maps - the options for number of asteroids; and the scenario/structures chosen will have a major impact on the performance of a given map too. Lots of asteroids or big buildings will be slower than a nearly empty world. Unlimited asteroids is also possible now too. In unlimited mode only asteroids you mine or build on are saved, the rest are just drawn arbitrarily using a proceedural "formula" and not saved anywhere.

Network lag
Well often this is beyond your control - but if hosting a game, or playing someone elses game - the dedicated server should be the best option. A dedicated server is busy working hard on all the network requirements, which leaves your PC entirely free to put its full attention into making the game play its best for you.. instead of you and.. those other 12 guys shooting at you.

There is a new configuration section called "Graphic Options"
Which have the following options -

• Renderer DirectX 9 or 11 - 9 Offers the best frame rate, but this option only exists if you are playing the legacy version or classic deluxe and you will not be able to use planets. DirectX 11 has better looking graphics and general stability with only a marginal loss in frame rate.
  
• Hardware Cursor - This uses hardware accelleration for the cursor, making it more responsive by being unlocked from the game frame rate. This would be the fastest option normally.
  
• Render interpolation - in digital camera terms this means double scanning the scene then averaging the difference between the two scans to generate an image at twice the scale. In PC terms however it is actually even more interesting. It takes the current physics state, (eg that item is floating 10 pixels to the left) and the previous physics state (that item was 20 pixels to the left), then generates a best guess position between the two to generate the graphical equivalent of a transition/average/half way point between the two (ok i will draw the item 15 pixels to the left then) It has the effect of making movement look smoother and more cinematic, by inserting extra frames but may make the game feel "rubbery" if you dont have a PC fast enough to get away with it.
  
• Enable Damage effects - this means damaged blocks vent smoke, sparks or toxic gas. Entirely Aesthetic. Fastest setting is off, but doesn't look as cool.
  
• Field of View - this effects how much you see in front of you, from 90 degree near bug vision to a fairly human normal 60 degrees, down to 40 degree tunnel vision. Obviously smaller is slightly lighter on the CPU. 60 or less should be fine.
  
• Quality Preset - basically a lazy way to set the following settings to low/medium/high in one click.
  
• Anti_aliasing - Fastest setting is off, but the game wont look as photogenic. This basically "softens" the look of hard edges visually.
  
• Shadow Quality - Low is the fastest setting but medium should be fine for most people. Mostly aesthetic.
  
• Texture Quality - this can effect performance by how detailed block surfaces look in game. Medium to low is fastest. But it wont look as pretty.
  
• Voxel quality - this effects performance by how detailed planet and asteroid surfaces look in game. Medium to low is fastest. But may make mining look and feel artificial.
  
• Anisotropic Filtering - basically a more efficient type of anti aliasing. Effects the sharpness of surfaces that fade into the distance. Lower is faster but makes distant items less clear.
  
• Multithreaded rendering - use more than one processing core when rendering. If you have the cores fastest setting is "on" if you dont have many cores fastest is "off" to prevent hyperthreading or FIFO deadlocks. (Note this option was disabled as of writing)
  
• Foliage details - Visual detail of trees and plants - only applies while on planets.
  
• Grass density - the complexity and lushness of grass on planets. Purely Aesthetic. Default is 1.0. But you can turn it down to zero if watching grass grow doesn't interest you.

These are some observations I noted as of 14/2/2016 in relation to offline and dedicated server sim speed, after auditing my main world.

Note: These did also appear to effect frame rates, (up to 10fps in some cases) but for this test I was only focusing on sim speed.

• Block mods appear to have minor sim impact (assorted guns, passive blocks, custom cockpits) had only 0.02 to 0.08 impact combined. Things like guns were not tested while firing however.
  
• Scripting only mods carefully made had almost no impact on sim (0 to 0.02 sim) eg. Admin mods, etc although during complex operations spikes were observed as would be expected.
  
• Block mods combined with scripted behavior had the highest impact, (eg teleport mods, mods with triggered events etc) in one instance a mod was consuming 0.40 sim by itself.
  
• Large stations have a surprising amount of impact on sim speed, particularly when in proximity to planets or asteroids. Before/after sim speeds showing anything from 0.10 to 0.20 sim impact.
  
• Welders or modded welder workshop items seem to have a massive impact on sim.. but only when turned on.
  
• large capital ships seem to take a bit of sim -(around 0.04) when stationary. More when moving as would be expected.
  
• The windows update bug mentioned earlier. In windows 7 home 64bit - a recent update can cause svchost.exe to use up 1gb of ram, and slow the cpu considerably. Stopping windows update services works around the issue. Microsoft apparenly have a fix for it, but it doesn't appear to work. This bug prevented the game from loading at all on one of my PCS until i halted the service.

For the following sections I am going to break it up into two areas. First below is a quick summary of things that slow down your games and some brief suggestions to deal with them. Then the section after this offers more detail on methods to deal with them.

Although I say the following with humor - it is a question you really need to consider -

When gaming seriously, you need to decide - is this a gaming rig or a fashion accessory?
Is your PC ready for action at a moments notice? Can it be booted and ready for action in under a minute?
Can you jump on the internet, start writing a book, or fly right into a game immediately?

OR is this more accurate -

You prefer your PC to look pretty, be all colorful with a slide show of random images, you have 12 seperate antivirus and malware tools installed, none of which you know how to use, some silly cartoon character pops up anytime someone comments on twitter, emails you, or posts to facebook - when new shoes or a rolex go on sale; the latest gossip happens or a multitude of other stupid things a popup jumps on screen telling you?

If you said yes to the preference for pretty, I suggest you sell your PC, and buy a smart phone or tablet - this guide isn't really for you. Buying the latest "fashion" in smart phones would give you more satisfaction. No really..

Ok getting serious again for a moment -
Not everyone has a PC to themself - sometimes all of the above may apply when someone else shares a PC with you. In this situation there is a solution - create a dedicated "gaming" user account. Then basically disable everything you dont need to play your game. In most versions of windows this can be done via your windows control panel. (under settings in the start menu, or in windows 8 using windows-key-X and choosing control panel) generally making this an "Administrative" user is best, and in some extreme cases, you should /downgrade/ the "other" users account to a standard user to prevent them installing junk. Another trick is to install a SECOND copy of windows on the same PC. Use this just for gaming. Configure a menu at startup to allow you to choose it. Easiest way to do this is simply install a second disk drive, or split your original drive into two partitions. Although doing this is outside the scope of this guide, keep it in mind in shared households.

Whatever category you fall into above, clearly you want to have your game run better so we need to get rid of the junk - so what is junk?
Pop ups?
If you are getting popups from spam or junk programs, even if you don't see these in game they are eating valuable ram, CPU and FPS.

Background images?
Your 138 screen shots of battlefield tea bag moments may be amusing, but do they REALLY need to be playing as a slide show in your desktop? In a game you can't even see it. Everytime that image loads or changes it wastes RAM and CPU, it ties up video memory and it also delays reads from your hard disk. It also generates something called an "interrupt" which often does not show in your task manager, but can tie an entire CPU core up for a few seconds; causing something known as "DPC latency" this causes games and audio to skip and jump; and network timeouts (ie lag) to spike at random.

What is using Audio?
Many people who were not around in the "dos era" of gaming dont realize that the sound card can tie up a computer quite a lot. Ideally when playing a game, close, or mark yourself offline in any other programs that use audio to minimise any conflicts.

Antivirus? Malware Protection?
Yup, as important as these are, they will actually slow your PC down, A LOT. as much as 85% in some cases. Either dont install them to begin with - which will require a lot of disipline to avoid situations where you may be infected -
OR make sure you only have 1 of each, and that it offers either a "gaming mode" or a "disable until reboot" option. Most "malware" tools only need to be used for a "manual scan" - they don't need to be running all the time. Also, NEVER install more than one Antivirus product if you must use one.

TIP:To avoid virus/malware never use IE or Chrome, never hit run/install etc from a website, don't use outlook, (the office component not the webmail service) never use a "download manager" if a website tries to force you use one to download their files, find a direct link to the file, dont use the "download manager" these are almost always malware payload installers

Peer to peer, weather, Instant Messaging or Chat
Any program running in the background such as Yahoo, MSN, Skype, Bittorrent, teamspeak, limewire, news, weather etc even if you are marked away will be consuming, CPU, RAM, and Network bandwidth. Anything that pops up is junk, even programs you use like skype.
Also windows is limited to a finite(aka very limited) number of concurrent "sockets" to a network. A single chat program could tie up dozens, resulting in very inconsistent online gaming.

Hundreds of Desktop Icons
You may think its convenient, or you are just lazy, but more than 2 or 3 icons on your desktop can over time cause a lot of slow down; as windows not only needs to refresh all the icon graphics for all of them regularly, it also has to overlay them on top of your desktop; and filter the text so the background is visible behind it. If you have ever copied a folder with hundreds of little files and wondered why it was so slow - it is because lots of little files require a lot of processing; the same thing happens when those icons on your desktop refresh.

Services and task scheduler
Windows has hundreds of services, from indexing to network analysis. While playing a game, you don't need most of these and they take up valuable RAM and CPU. Also there is task scheduler, which can do anything from start a virus scan to a disk check at random.

Startup programs
If when you first start windows you have an hourglass for 5 minutes, and more than 5 or 6 icons appear in your system tray; then you are loading more things than you need to.

Windows update
It is always recommended that you keep all your security updates current - but really does it matter while you are in the middle of a game? Windows update consumes a lot of network, hard disk and cpu traffic while running.

Virtual Memory
With Vista and onwards Virtual memory is less of an issue, but there are some tricks you can use sometimes. Often the swap file is not setup as best it can.

Windows "theme"
Sure it looks nice and all, but it also uses up a lot of CPU. You can sometimes gain an entire point of "windows experience" simply by turning this right down.

Windows Media Player Network
If you open your task manager you may notice a process called WMPnet or similar. This is a throw back from Media centre in windows xp. Be sure to disable this prior to playing any game, or even perminently; this can take up to 40% cpu; and all it does is allow your xbox (or other windows compatible devices) to list over network the media/music in your PC. Disable the Windows media Centre receiver/scheduler and Windows media player network sharing service. File sharing will still work, and your cpu runs better.

Solutions?
Get rid of Pop Ups
Firstly uninstall everything you can, use the "programs and features" or "uninstall a program" control panel in settings under start menu (or windows key-X in win8) and uninstall anything marked Conduit, Toolbar, Mindspark, and most "LLC" company named products should be considered suspect. Wierd names with "altErnAting" case should be considered suspect as well.
Once you do that, run a tool such as Malwarebytes anti Malware, and perform a FULL SCAN" once everything is removed, consider uninstalling Malwarebytes or whatever tool you used afterwards. Finally check all your web browsers "add ons" section, disable everything you don't recognise. Only enable it if a website you use specifically needs it. Eg Flash player, java, pop up blocker etc. You may need to dig deeper here, run a full anti virus scan too. I once found over 5000 nuisance programs and fragments on a single PC. It was a wonder it even started up.

Forget Background Images
Sure they have brag value but you cant see them in game - turn them off entirely.
In windows right click your desktop, and choose either properties or personalise depending on your version. Then Choose desktop background. In windows 7 it looks like this:
Once you are in there choose the "picture location" option and choose solid color like this.
Save the changes and close it.

Remove or Disable Antivirus? Malware Protection?
Uninstall any /extra/ anti virus programs, and malware protection software if you can.
Make sure the antivirus you have has a disable option - and use it prior to playing games - Ideally having none installed at all is better. But you cant always. Also go into your windows defender etc settings and disable it (look for the "use this program" option) also disable scheduled scans. Program rarely catches anything, and the performance trade off is not worth it. In the security centre screen there is an option to "disable notifications" to stop the popups saying you have no virus protection. That popup itself can cause issues.

Peer to peer, weather, Instant Messaging or Chat
Just remove them if you can. This is a gaming machine not a news room or mothers club meeting. If you need them, check in their settings and disable any "load automatically" or "start when windows starts" options. Then only run them when you need them, not all the time.

Hundreds of Desktop Icons
Be strong, do a clean up of what you dont need. For everything else there is a simple solution. Create a new folder on your desktop, and move them all into that. That way they are all still there, but they wont be refreshing continually with the desktop.

Background processes
Check task manager or use systweak process explorer, see what uses up too much CPU. Google anything odd.

Services and task scheduler
Take the time to go through the task scheduler - it will take a while - but all the rubbish randomly firing off that you get rid of is worth it. For services, you have two options. The easy option is install a free tweak tool like jetboost or similar (assuming you trust it) that shuts off all non-critical services short term on request. Or the other option is to systematically go through them all and disable them in the MSCONFIG tool (refer startup programs below)

Startup programs
The simplest way to stop random junk loading is run a tool called MSCONFIG. press windows-key-R then type "msconfig" hit ok on the UAC prompt and go to the startup tab.
(in the case of windows 8 - it is built into task manager, use ctrl-shift-escape instead)
Generally for a gaming machine, you can safely untick almost everything under startup. The only exceptions would be software for printers, game controllers or network devices - and most of these still work without the system tray icon.
There is also a "services" tab which allows you to disable services. You need to be very careful in here. Things like messeging, windows media player network sharing or indexing can usually be left off. On a desktop if it has no wireless - wireless zero can be disabled too. You can also hit "hide microsoft", and what is left should only be services for steam, printers, networking, graphics, security etc.
For a more detailed list of startup modules, download a tool called "systweak autoruns".

Windows update
I would suggest setting this to notify only and manually run windows update. Install every offered update and reboot. Once you have all updates, prior to playing games, turn windows update off. This will conserve a lot of internet bandwidth, and prevent accidental "reboots to install a critical update" while in a game.

Virtual Memory
In XP, set the swap file to be double the size of installed RAM, and if possible place it either on a second partition, or a second physical hard disk. This ensures that it runs as fast as possible should the PC need to swap out.
In windows Vista and newer the size is less critical, but if possible place it on an SSD, a second hard disk, or a faster part of the hard disk. Also ensure the swap file is not fragmented at all. This can be achieved by TURNING THE SWAP FILE OFF ENTIRELY, then running a full DEFRAG of your hard disk, then TURN THE SWAP FILE ON AGAIN.
The swap file settings are located in the "advanced properties/advanced performance options" which is accessible by right clicking "my computer" or "computer" in the start menu, and selecting "properties"

Other tweaks
Windows "Visual Effects"
Ideally turn off all unneeded Effects. They are decorative and slow the pc a lot. The simplest way to do this is in system properties; advanced/performance settings - the screen looks like this:

Disk errors!
Check your disk for errors frequently. Index/cluster errors can cause terrible hard disk performance. You can do this by right clicking your hard disk icon (in computer/my computer) and choosing properties, and tools tab.
In there choose to check for errors, and choose to search for bad sectors, it should offer to schedule a startup scan.
Say yes, then reboot.

Defragment your Hard disk
Windows Vista and up should do this Automatically. But due to default power saving settings, which put the computer to sleep or hibernates, the conditions for it to run almost never occur.
To force a defragment now as above go to the drive properties, but instead of checking for errors, choose the defragment option.
A defragmented disks more efficiently reads files. In our case your game files.

Power management
A number of options that severely effect the PC speed exist related to the power management. Even experienced tweakers can overlook this -
The two main areas to watch for -
"Power options" in here make sure you have the "performance" profile selected. In some laptops you may need to use the software supplied by the maker to set this option; and it may contain options relating to the "discrete" and "performance" GPU. (these laptops have dual video chipsets, an economical "discrete" mode and a performance "nvidia/ati" chipset mode)

"Device manager" bring up all network device properties, USB, and video cards, and sometimes sound cards, if they contain a "power" tab make sure the "allow windows to turn this off" option is not enabled.

Items in here don't fit anywhere else in the guide.

Make your PC start almost as fast as booting an SSD - without needing one!
This trick I use frequently, although it doesn't necessarily make the games themself run better, it allows you to load windows much faster - subsequently less waiting required before you can play the game!

This trick works brilliantly on XP, and in many cases Vista and Windows 7. Early builds of Windows 8 try to do this by default, but hides the fact that it is doing it. Some PC's do not support this option either due to BIOS settings, or simply OEM defaults. But if yours supports it, USE IT!

Basically - go into your power control panel, and locate the Hibernate option. In XP it is a dedicated tab, in Windows Vista and up, it's buried in advanced options. Where ever it is, ENABLE IT.

Then go to the section "power buttons" or "what the power key actions are" etc. Assign the action "Hibernate" to pressing your power button. Save and exit.

Now close any programs you don't need open - then tap your power button (Don't hold it down, just tap it) Depending on your PC it will take between 10 and 30 seconds to turn the PC off, sometimes more if you have a lot of RAM. Interestingly it is still this fast even if your PC normally takes minutes to shut down.

Once the computer is turned off, it is REALLY turned off, not just in sleep mode, you could even unplug it if you wanted.

Now, turn the PC on again - you should see a different start up screen, then in about 10-20 seconds, you should arrive at either your login screen or your desktop. The PC is now ready to use. Really, it is THAT FAST!

You just need to remember to tap the power button to shut the PC off any time in the future you are done for the day. Occaisionally you will still need to shutdown normally (updates, new software etc) this can still be done in the start menu (or side bar in W8) as normal when required.

How does it work?
Instead of taking 3-8 minutes loading all the individual windows programs, services, and drivers, one at a time - what it does is a "memory/cpu" dump to your hard disk. As it is writing a single file, it creates this file very quickly. It then sets a startup flag to load this dump file, then turns off.

When you turn the PC on again, it grabs that file, and simply loads it all into memory and CPU in a single read. (remember what I was saying in a prior section about lots of little file reads (ie your desktop) slowing the PC down?) Because it is loading one file instead of lots of little random files, it does this very very fast.

Troubleshooting
There is a side benefit to using hibernate - it fails if there are any rogue programs tying up your CPU or Disk. In this case it will give a warning that "XX program/task is preventing the PC from hibernating" If you get this, find the rogue program and either disable or get rid of it. This program will also be interfering with your games!

Own an SSD?
Windows has something called "readyboost" how this works is it uses flash memories ability to read from random parts of the disk at the same speed, without delays like you get with conventional hard disks. Ready boost simply puts all the small regularly read temp files on this disk, and reads them from there instead. If you have a high speed flash disk or usb 3 flash drive give it a go. You can get the same effect by changing your "temp files" (from system performance control panel environment variables) location to point to a flash drive if your OS doesnt support ready boost. Works just as well with an SSD as it does a USB3 high speed flash drive. Also putting your swapfile on a proper SSD and disabling the one on the normal hard disk will also make a lot of difference.

Own more than one SSD?
What is faster than an SSD? Loading two parts of the same file off TWO ssd's -
There is no reason why you cannot combine two SSD drives in a stripe or Mirror RAID, and when you do, it almost DOUBLES the read speed. RAIDS can be created two ways - using a hardware RAID (refer to your mainboard manual) or a software RAID (refer to the windows disk manager documentation)

Cheap Dirty Frame Rate boost
Use this only as a last resort; you can gain about 20% frames per second, by DISABLING your sound card. Well coded games detect the lack of sound hardware, and disable its entire sound API - giving the game performance a major boost. The obvious down side is however- you will have NO sound in your game!

General across the board performance improvement
When defragmenting your hard disk, often your /REGISTRY/ is not defragmented. A registry can become fragmented in two ways:
1: Physical placement on disk - this file is locked when defragmenting normally, as such it will always remain fragmented.
2: The internal structure of the file may be very sloppy due to adding/removing program settings over time. When making changes it often writes to the end, leaving a gap in the middle, much like SQL databases where a deleted record is actually just marked "free" and not actually removed. Windows continually reads and writes to this file, so the sloppier it gets the slower this makes the PC.

To fix point 1:
Reboot using a Live CD or USB stick, then perform a full defragment of the hard disk using something like defraggler or the built in defragment tool of the Live Software. As you don't boot from the hard disk, the registry files are not locked.

To fix point 2:
You will need a registry defragmentation tool. Auslogics (Boostspeed etc) has one. How it works is as follows:
It exports all the active keys into a temp file. It then loads a clean "blank" of the registry, and writes them all into it. This file then replaces the original. In windows 95, 98, ME, NT, 2000, XP you could do this by manually exporting all the keys to a text file, booting a floppy disk, and moving the "failsafe" "repair" or "recovery" copy of the registry from the windows folder into the main system registry folder; reboot in safe mode, then "import" this file back into your failsafe version. The failsafe version was usually created when the PC was first installed with windows.
In Windows Vista and up, unless you have a restore point from your original install, you will need a utility to do it for you.

Why this works is when writing it back, it sequentially writes them all at once, instead of jumping around adding/removing keys at random leaving holes everywhere. This also reduces the size of the registry file (critical in windows 2000 where a size limit could prevent it booting) without removing any settings.

Don't Accept Defaults
Most Modern Video cards come with a bunch of presets that while they may make the game look pretty, generally waste memory, and frames per second for the sake of generic compatability.

While admirable, if we wanted compatability you would be using the on board video.

Both ATI and NVIDIA have "advanced" settings, that many pay-to-win gamers don't even know exist.

NVIDIA generally has more settings, but ATI has a handful as well.

Nvidia also has a lot of other hidden settings like the "coolbits" clock speed control, and a number of pipeline settings you usually need to hack (eg riva tuner, or reflash) to enable.

To access the non hidden settings either double click the nvidia icon in your system tray, or right click your desktop and choose nvidia control panel.
If it asks you do you want advanced options/mode say yes.

Depending on your hardware you will have some settings top left you need to note -

• Adjust Image settings with preview
  
• Manage 3d settings
  
• Configure Surround/PhysX/SLI

There are other settings but you can ignore those as they wont effect performance.

In adjust setting with preview - select "use my preference emphasizing" if you have a low end budget card, drag the slider all the way to the "performance" side.
If you have a mid range or high end card choose either Balanced (middle) or Performance (left)
Hit Apply.

Next move to the "manage 3d settings" section, and choose "global settings"
In here you have a number of settings, I would suggest on a low end card to set:
Occlusion off
Anisotropic filtering off
Antialiasing - set them all to off
Multi display/mixed GPU - set this to single display mode unless you have more than one screen
Power management - prefer maximum performance
LOD bias - clamp or allow (test in game - some cards might cause games to look odd with anything but clamp set)
Texture filtering - high performance
Texture filtering trilinier - on

On a mid range or better card -
Occlusion - depend on if supported by game - - performance
Anisotropic filtering 2 4 or application controlled
Antialiasing - FXAA - on, Gamma - on, Mode - override, setting 2x,, transparency off or multisample
Multi display/mixed GPU - set this to single display mode unless you have more than one screen
Power management - prefer maximum performance
LOD bias - clamp
Texture filtering - high performance
Texture filtering trilinier - on

Configure Surround/PhysX/SLI
If you are running a single card, or two missmatched cards -
you will see this:

• If you have two cards set the PhysX Processor to the second card.
  
• If you have a single card, you can leave it on Auto select.
  
• If you have a high clock speed multi core CPU, it may be faster to set this to CPU, then overclock the video card.

There is an additional SLI option available if you have two matched cards with an SLI cable, this will be mode: PhysX or SLI. Set it to SLI in this case. Other options may be available if you have a different driver version.

TIP: If you find options like LOD bias work better on some games and not others, click the "program settings" tab here you can set specific options for specific applications/games

People often tweak their windows, but completely overlook their system bios.

To access you bios on turning your PC on immediately hit DEL, F1 or F2 (depending on your mainboard, it should show on screen what to hit)

In this area, you need to be very careful, and note what you change. This is a very scary place for some people, but generally there is a number of settings you can safely mess with.

Items Marked with an * are safe to touch, other items may be risky.
Items not mentioned here, should not be touched unless you know what you are doing.

Generally you want these options set:
XMP - this uses the overclock settings decided by your memory manufacturer and runs your RAM at a higher speed. Note: this will significantly increase the heat generated by your ram, and in some cases will cause booting problems. Keep in mind most ram is already slightly overclocked from factory, XMP sets it to eXtreme Memory Performance settings. You may need heat spreaders for your ram if you use this.
* hyperthreading / all cores - enabled etc. (this allows you to use all of your CPU capability)
* memory remapping - enabled (this allows you to use more than 3.25GB of ram)
* if you have on board video which you dont use - disable it, or set it to use less system memory (frees up ram)
* boot Rom/network boot - Disable (speeds up boot up time slightly)
Memory apparture setting, set this to the highest it will accept. (mainly for AGP, but sets the size of the memory pipeline to your video card, bigger means textures feed in faster)
DISABLE - on board serial and parallel ports. (unless you use them this frees up some ports and IRQ's which reduces DPC latency issues with shared resources)
DISABLE - on board floppy controller (unless you have a floppy this frees yet another IRQ)
ENABLE - legacy USB support (means your USB mouse and Keyboard is available immediately)
AI overclock/ hypertransport /atu - ENABLED (just enables if any the ability for the CPU to adapt its clock speed on the fly)
CPU Frequency Multiplier - AUTO (unless you know this is wrong this tells the mainboard to operate the CPU at its rated multiplier)
* CPU Cache level 1/2 etc - ENABLED (the ability for your CPU to effectively queue/cache processing requests / commands)
* System performance - Optimal (runs the cpu using the ideal performance options)
Selective overclock / Boost / etc - Set to either "On" or "5%" if supported. Dont go higher unless you know your cpu cooler can handle it. (Generally the amount that the cpu will scale its speed up if the CPU has maxed out.)
Memory Frequency - default is Auto - but check your ram clock speed, often "auto" selects "lowest supported clock" you may want to set this to the "rated" speed of the ram. (this is the clock speed that the ram is operated at; faster means programs load quicker)
* Onboard game port - Disable (allows you to use the old joystick header port - unless you have one leave it off to free up more resources)

People think they know what they are doing installing a video card but here are some common tricks people often get wrong

• 1: Always install your fastest PRIMARY video card in the FIRST (closest to CPU) PCI express (x16) slot. The other slots often have reduced speed or capacity. (See footnote below)
  
• 2: When upgrading your video card - If you have more than one PCI express slot, and run NVIDIA cards - install your Second Fastest(old) video card in slot 2 (second slot from cpu) or slot 3 - even if it is a different model to your PRIMARY card (which means you cant use SLI) you can often still use it as a dedicated PhysX card or for number crunching using special distributed.net applications. (set it in your nvidia control panel as the PhysX card)
  
• 3: If forced to use an older video card, (eg your "good" one blew up) - but you have a multi core processor, sometimes setting your CPU as the physX processor in the nvidia control panel will work better. Test with it on and off on games with lots of explosions, see what gives best FPS. This will also allow your card to run slightly cooler - meaning you can overclock it more.
  
• 4: Avoid jamming cards next to the Video card cooling fan. It interferres with cooling.
  
• 5: Most nvidia cards can be safely overclocked up 10% with good cooling. But you will need to install the "coolbits" patch.
  
• 6: Dont forget the RAM can also be overclocked.
  
• 7: Some nvidia cards can be reflashed to the next model up - enabling additional pipelines, and saving you hundreds in price sometimes.
  
• 8: If you have two cards of the same type, and an SLI cable - if you install them both remember to go into the nvidia control panel, and TURN THE SLI ON! This may seem obvious but the number of SLI PCs i've worked on with it turned off is astounding, driver updates also can disable it!
  
• 9: When running either two cards or one or more cards that require an additional power connecter, make sure your power supply is 80+ rated; and if using a PCIX power molex adapter, make sure you dont plug it into both molex connectors on the one wire. Each connector should be on its own power rail wire. Otherwise you risk blowing out a power rail in your power supply.
  
• 10: When buying budget cards, ignore reviews, often the card reviewed has the same model name, but a different chipset. Many Oems use this trick to sell more low end chipset cards. Often there are two models with the same name, and one is basically a counterfeit. What you need to pay attention to is in its tech specs - does it run a 64/128 or 256 bit pci express interface. Even a low end chip will work well matched with a 128 bit interface. Some budget cards run dual 64 bit pipelines to give it 128 bit, doubling its texture streaming speed. Others just run 64bit end to end, halving it. See footnote below.
  
• 11: Cleaning - the cooling fans often blow into a very small heatsink, which makes it very easy to accumulate dust in there. Enough dust and you may as well have no cooling at all. Which leads to screen glitches, lockups, and cards wearing out prematurely. Make sure you get in there with a brush or canned air, or remove the cover and clean out any accumulated dust, in general it will take about 4-6 months of heavy use to start building up dust, so check and clean the fan out twice a year. ** Incidentally this also applies to your CPU fan, intel CPUs "UNDERCLOCK" automatically when they get too hot. So your 3.4Ghz Death Machine of Doom, could in reality be running like a 1.73Ghz Noob Knob of Embarassment.

Footnote:
PCI Express Considerations:
PCI Express has several variants -
×1, ×4, ×8 and ×16. The x16 is a full length slot. There is also a newer x16 variant with an extra connector. The x8 could come in a full size x16 length but only run at x8. Or a smaller half size slot that runs at x8 or x4.

The majority of 3d Graphics cards use an x16 type connector - but will not necessarily run at the full speed. A video card could run anywhere from 64bit, 128bit 256bit and all the way to 384bit. Generally sub-$100 cards run 64bit, sub $200 cards run 128bit, and cards over $200 could be anything from 128 up to 384.
Just to confuse matters some motherboards could have one or more x16 sized slots - but are running some or all of them at only x8 or even x4 capacities. Check your mainboard manual carefully. A 128/256/384bit video card will still work in a x8 capacity x16 sized slot; but it will run like a 64bit card!

One of the commenters below pointed out an important point as well -
In short - the speed of your PCI-X slot does not necessarily effect your FPS. It sounds stupid, but it is technically accurate. A GPU will run at whatever its rated speed is no mater how slow the express slot is. Much like a car motor has a certain range of RPM and torque, irrespective of the gearbox or wheel size. What it WILL effect however, is how quickly games/levels load. A game caches a bunch of data, including textures etc. Once it is cached, very little performance is required for the PC to tell the video card "load precached texture X on wall object Y, set angle to 45 degrees from player, etc etc"

A good example of this is when a map change is triggered on an online game - some players load the new level almost immediately and are already playing by the time you are on the map. Yet, you may have a great frame rate while playing. But waiting for the level to load takes longer. (Disk /CPU performance also effects this too)