Hi there,
Did you find a solution? I started experiencing the same problem after update 6 about a week ago. I tried EVERYTHING, even an update to Windows 11 and a complete deletion and reinstall of MSFS2020 (Steam version). I am stuck in the menu with a FPS on 2.0 “Limited by RdRThread PC”. Before update 6 I had FPS of 25-30 in High-end setting.
Ryzen 5 3600 CPU, 32 GB ram and RX 5700 XT 8 GB GPU