One thing I just noticed with today’s build (.2.13) is that my performance seemed quite good compared to previous builds. At first I thought maybe some kind of optimization had been done, but I actually discovered that it was because my truck traffic was much lower than previously due to the fuel changes. I still had some trucks on the road, but it seemed like they were actually limited by fuel and so there were less of them driving at a time. This gave me a boost from ~20-30 FPS to 60-80FPS, which felt great.
Whenever fuel reserved climbed enough for a full burst of truck traffic things shot back down though, so it seems like the path finding, fuel, and pollution calculation introduced by trucks add up quickly as more of them become active. My city has 55 employees, 34 citizens, and trucks for at around 27 of them just a rough size benchmark.
I also want to chime in more generally on the point of the OP to say that it seems like my system is CPU/memory speed limited with regard to the games current performance. That may be something you all are already aware of, but just like @administrator1 my GPU doesn’t run at its nominal maximum frequency nor does it have high utilization (indicating its waiting on some other part of the system before it can work). System specs are below in case that’s useful.
AMD Ryzen 3600X CPU
16GB 3600 MT/s RAM
AMD RX 5700XT GPU
Game is running on an SSD.
3440x1440 output resolution