SPOILER! Kattints ide a szöveg elolvasásához!hmm, ok, that’s more information I see below you already have an answer - but with you one has to find out what is limited !
RTX 3090 with 32 Core AMD Threadripper and your frames are down to 15-20 ?
I haven’t seen this with my system - as I mentioned above 3 x 27". @5760x1080 and I can keep 33 FPS constant almost everywhere (sporadic break-ins during loading and I have activated the ReShade profile or Nvidia Ansel, also takes a pair of frames)
I would start with the approach of looking at workload, memory usage etc. to find out where it’s bouncing.
Whereby we still partly have a “FSX” in the base of FS2020, even a 100core CPU is not faster - not really optimized for multi-core support yet, could be. Maybe it will change with DX12.
Yes, the Threadripper is a monster - no question about it, but the SingleCore performance is not really “high”, compared to certain Intel processors, will probably change with 5000 series from AMD.
Apparently the “old”, “good” SingleCore performance is very important (as you can see from various forums and results), but it doesn’t have to be.
Try to reduce AI (also cars etc.), display radius etc. and try again and again.