VR issues due to new lighting incompatible with steamVR?

[FoxDelta]

having very reduced frames since 2.5.6 , as many i guess

 

just tried this modification https://forums.eagle.ru/showthread.php?t=269320

 

and disabled all motion smoothing in steamVR completly, under video, setting per app.

and getting much better (of course - motion smoothing cuts them) but also smoother experience

 

can it be that this stutter issue is related to something introduced incompatible with the way steamVR is doing motion smoothing??