SteamVR stall on WaitGetPoses


We are having issues where the WaitGetPoses() call from SteamVR is taking a long time and causing poor framerate. According to their documentation it will wait for the previous frame to end. We see however that when profiling in Unreal our scene render time is normal and no such thing should happen:

100.0%21.48ms FRAME
44.8% 9.62ms Scene

This function is called right before rendering at RenderViewFamily_RenderThread->PreRenderViewFamily_RenderThread()->GetCurrentPose(), which is UE4 standard and is right before rendering as is recommended by SteamVR.

Some input greatly appreciated!