In my case I use 4.8.3 engine to play oculuse dk2 in Kite Demo.
in Selected Viewport Play mode all game is performance exactly.
but when I use VR preview mode there are following problems:
1, input orientation is totally opposite. such like you are input move forward the character will move backward.
2, In the bottom screen have some strange texture in there.
This is a known issue (UE-16673) and it has been submitted to the developers for further consideration. I have provided a link below to the original post. You can check that thread for future updates. Thank you for your time and information.