Confirmed.
Something broke the BFM campaing performance after 2.5.6 update. My FPS is somewhere between 15-20, regardless of graphic settings - and with VR it goes to single digit FPS counts.
So far I have tried updating 3D drivers, deleting the shader folders and rebuild them. However, none of it had any effect. The PC is pretty high spec with SSD, 32 GB ram, 2080ti and i7 @ 4Ghz. Things usually run as smooth as they ever get in DCS.