Before Hotfix 1.15.8.0 I had good performance in the cockpit whilst sitting on the ground - about 30 FPS (I lock my monitor to 30 FPS).
Now after the hotfix I have 18 FPS in the cockpit. This happens in every aircraft I try.
Strangely though, once the aircraft starts rolling down the runway, the FPS increases and is ok for the rest of the flight UNTIL I land and slow down again to taxi speed where it drops back to 18 FPS.
Reducing graphics settings has no effect.
ASUS 10900K, RTX 3090