Win10, dedicated MSFS (dual boot to separate SSD). It was that bad. Normal FPS in 4K (no VR) is in the 45-65 range. I use VR with MR on, so 22.5 mostly :-). 5FPS was with no VR, VR was completely unworkable. Menu sluggish, could not click buttons, had to try 10 times to make it work. 3 reboots - same thing. Reverted to old drivers - Instantly back to normal FPS.