Windows Mixed Reality vs SteamVR to handle OpenXR : what the heck with motion reprojection ???

[flyingcyrus]

Hi there !

I always noticed that DCS didn't perform as good with WMR / OpenXR, as when I was using SteamVR and OpenVR. Lot of small and random stutters compared to the butter smooth experience with the latter. It appears that after setting SteamVR to handle the OpenXR API, things are smooth as silk again !!!! This afternoon I ran some tests so see what's wrong with WMR/OpenXR... The result is quite surprising.

When using WMR / OpenXR with Motion Reprojection activated, simulation time is on par with frame time (around 22ms) :

When using SteamVR / OpenXR (motion reprojection activated), simulation time drops to around 5ms !!!! WTF ? :

The thing is, when disabling MR, the simulation time in WMR / OpenXR drops to 5ms as well ! : 


So it appears, correct me if I'm wrong, that WMR has very peculiar way to handle the reprojection, a way that literally is milliseconds hungry !!!

Some might say this is a bug in DCS counter when motion reprojection is on (why only when WMR is in charge of the VR API then ?), but the fact is that in one case you have stutters all over the place (despite a FPS stuck at 45) and in the other case they're gone !

Did anyone else experience this ?