That’s because you’re getting 90fps in the clif house AND every one of those 90 frames knows where your head is at that time.
If you drop frames then it will stutter, if you add reprojection it’s guessing where your head is so it will stutter. I’ve got it pretty smooth now but that’s because I’ve overclocked everything 
with reprojection and to try and render 45fps in VR which is keeping everything smooth in my G2.