I've been having the same issues, have been updating drivers and what not.
Now I upgraded my windows to 11 (from 10x64 pro) and it seems to have cleared the issues with stuttering in menu, and in game for the first 30 seconds.
Then they returned, and the stuttering increased more and more the longer I drive.
I then disconnected my wheel Fanatec CSL DD with a F1 2.5 on it, and the CSL V3 pedals connected directly to the pc.
Now I can drive no problem with the keayboard. no stuttering.
Whilst the wheel was connected I found that turning it in menu, would make the music stutter!
In VR the track is black, but hud will show, in menu it works fine.
I would try disable stencil in VR settings, but it is greyed out.
I've appended DXDIAG.txt