I base this guide on my own experience: when playing skirmish space battles or galactic conquest, if I encountered many “elements” in a huge battle or had a map with a lot of planets, usually my pc used to get very slow and fps decreased rapidly. Most of the times the game got unplayable.

Feel free to disagree with the workaround I propose, on my computer it worked, maybe on yours won’t so I’m just sharing this and I am not imposing anything, feel free to disagree in the comments giving constructive tips and explanations.
This guide is meant to be basic to be understandable to most but useful to the more technological persons as well.

My computer specs are:
CPU: Intel Core i7 6700K @4.00 GHz
RAM: 16 GB RAM DDR4 HYPERX FURY
GRAPHIC CARD: AMD Radeon R9 380 series
OP SYSTEM: Windows 10 64 bit

If you look at my pc specs they aren’t of a monstrous pc, but I would say it isn’t a potato as well; I use it for engineering calculations for university tasks and it’s fast and reliable.
Sometimes I play Battlefront II (2017) with graphics set more or less to high and it has no problem at all.
But if I play Empire at War, more often with mods, whenever the screen fills with many units, everything starts to slow down.
Well, at first I thought it was due to my graphic card and tried to change the graphics parameters; first I tried IN-GAME, but nothing happened, the models got low polygon but the game remained slow and every laser shot was spurred every five seconds (like in slow motion more or less).
The second time I tried changing the graphic parameters from the graphic card interface (in my case Radeon Settings) but still nothing happened.
After all, if my graphic card can stand Battlefront II, why it couldn’t a game of ten years before?
Maybe the graphic card isn’t the problem.

I looked on the net and found many people that had the same issues, and to my surprise, many had just a good desktop PC just like me. On reddit I found a guy who told that Empire at War Gold engine was created for 32 bit architecture and system with just one CPU CORE.
The tip he gave was to impose to the game the usage of just two cores. If you go on the game page on Steam, under the Recommended pc stats for the game, you see that the CPU recommended has just 2 cores.
As you can imagine, my first thought was “hey, why should I use less cores if I’ve got a CPU with eight that can stand many more calculations than my old laptop with a Pentium processor?”
Well, the answer is that even if using less cores looks a dumb thing, as you can see from the game stats 10 years ago Dual core processors were common so the games used to be conceived with that architecture in mind.

If you have a multi core CPU (nowadays more or less any desktop PC has it) and Windows 10 you just need to
1. Open Empire at War Gold from Steam (or the mod you are trying to use)
2. Let it load until the start menu screen then click the windows button on the keyboard
3. Right click on the Windows symbol and open the task manager
4. Go to the “Details” tab
5. Look for the game process and right click on it
6. Clicking “Affinity” you get to a description of how many processors the task is going to use (I had all of them active
7. Check only two of them (I choose 0 and 1)

Another tip I used was changing the game priority so that the system devolves more “resources” (like memory and CPU usage) to the game.
From the same tab as before (“Details”) right click on the game and change the priority.

DO NOT CHOOSE REAL TIME IF YOU HAVE A POTATO PC but just high because real time makes the system unstable; on the contrary setting high just tells our computer to consider the process more important than other processes.

On the contrary, if you have a strong computer like me, I tried setting the process to real time and it made it super fluid and with no crash at all on the system.

I have an AMD graphic card and recently I found a label that fixes your frames per second.
I applied 60 FPS so that I maximized the graphics but, as soon as the graphic card senses there is a low frame rate, it automatically changes the resolution so that I ALWAYS HAVE a fluid video experience.

This is how I made it with the application for my graphic card


as you can see at the bottom there is a line where I can set the frame rate control.

For those who don't have an AMD GRAPHIC CARD, try surfing the web and look for this property for their graphic card.

With these tips, I finally got it! Even if the graphics are set almost to maximum (after all my graphic card can stand a 10 year old game, don’t you think?) the game runs smooth and even in huge battles with AI set to maximum and using mods with many changes (such as Imperial Civil War or Awakening of the Rebellion) the AI starts to make tons of calculations but never slows the game.
Hope you can be satisfied just like me, if you found these tips useful remember to rate this guide so others can try and maybe find a solution.
I’m not English so If you found some mistakes I’m sorry, hope you can understand and follow the guide nevertheless.