Does MSFS 2020 use multiple cores?
MSFS uses only 4 cores, so having a fast 8 core CPU is better than a slower 24 core CPU.
(2) More CPU Cores runs Flight Simulator (2020) better? - YouTube
Well, in Win11 on DX12 and a 12900 it does. It doesn’t translate into a huge performance benefit (at least not in terms of fps), but like I said the sim runs (or used to run before b3) much smoother on DX12 vs DX11.
Test your mods, I’ve done some while otherwise vanilla and IMO that is most likely where any problems lie. The default aircraft fly great in DX12 which can’t be said for my glider.