There are a couple of easy ways to do that. For quick testing you can just open task manager, go to the detail tab, and right click a process (dwm.exe for example) and select “set affinity”. You can then uncheck cores 0 and 1 to prevent that process from competing with MSFS for cpu time on those logical cores. Dwm.exe and the WMR processes are multithreaded and will use multiple cores, so I just prevent them from using the first physical core, so that MSFS can have that one mostly to itself.
If you want a more permanent solution, along with a number of other nice performance tweaks, you can use the free version of Process Lasso to do the same job. I allow MSFS to use all cores except 0 (assuming hyperthreading is enabled) and force the following processes to not use cores 0 and 1… (assuming WMR/Reverb G2)…
For Oculus I would do the same thing with their processes. Motion reprojection and ASW are very cpu intensive.
I have found that keeping those processes from competing with MSFS for core 0/1 time really helps smooth things out in the sim. Also if you do end up using Process Lasso I would recommend disabling “Windows dynamic thread priority boosts” on flightsimulator.exe. On my machine (i7 6700k and 3090) disabling that has helped relieve some persistent stuttering. Additionally, starting Process Lasso after the sim has fully loaded works best. FS doesn’t like being core restricted on startup, usually crashes if it’s not allowed to access core 0, but it has no issues with having its processor affinity being changed once it’s running.
Btw, this is assuming a Windows 10 install. With Windows 11 I have no idea if these tweaks are still applicable, given the new thread scheduler coming for it for Alder Lake etc.