Been following along other threads to overcome the latest performance obstacles due to Asobo releases and have tried most of the suggested remedies, the latest being removing the overhead menu bar. I too, had a very well running sim before the last Asobo upgrade. My system is a 9900K with 32 gigs of 4250 ram, m.2 hard drive, 3090 EVGA running a Samsung 27 inch 4k monitor at 30 fps or 60fps, what ever worked for the flight and I was using basically Ultra settings with the exception of a few personal preferences. With the latest suggestions from other simmers implemented, I found I had to still roll back my ultra settings first, most are on high now and the big 3 are 100 / 150 /150 . Even traffic and ships are rolled back. With this done, I was any where between 29 to 43 fps. Not bad.
Today I installed Shut Up Windows 10 from O&O software, free download, and I had an additional gain in fps. My developer fps counter went from main thread to gpu bound and now rotates between the 2 based on location. This is not a huge find but one that might help some. I few fps here and there and pretty soon it starts to look like a usable sim again. I was always bound by main thread and the Shut up program has killed enough back ground services to get me gpu bound which is my strong suit I would say. Give it a try see what you think. Skip