Here's a post I just made in response to another question someone had. Thought it might be useful to share it more generally...

I'll give you an example of what a vast difference, just the number of roads you have makes.
I've played on the same map I made for about 2-3 years now, tweaking and shaping it... Barely. It's an almost completely flat map where the main 25 tiles I use, is 99% flat and is mostly land with shore all around it.. Based on THE GREAT PLAN map by Mulleboy

I used to play normal with just the highway infrastructure in place and had a basic setup of progression for the whole game I kept replicating.
In the beginning of the game as I layed out streets, my pc would use about 10.5 - 11 gb of ram.
As I got further into the game, by the time I unlocked airports and/or had populations over I think? 75k, it would rise to about 12.9 gb of ram. And by then I was usually done playing about that level...

Then I decided to create the 2 main cities and 3 small areas I always built in almost exact detail, as part of the base map for the begging of the game to save time and aggravation on pc potato...

Instead of starting at about 11 gb, the game, without playing it for even a second would start at about 12.5 gb with ZERO population... By the time I reached the airports unlock with similar populations, it would still only rise to about 12.9 gb as before.

That means the road layouts alone were responsible for about 75% - 90% of the ram usage without even playing a seconds worth of gaming.

That was a heck of an eye opener that might be useful to alot of people.

Does anybody have advice about gameplay habits that might help people see where they can save resources or improve FPS in game simply by changing their habits in game?