When i run in selected viewport mode - the draw frame time bounces between 1.5 and 3ms.
Then once i go into “VR preview” the draw frame time goes up to 10.85 ms and fluctuates to about 11ms.
the game frame times are around 6ms and gpu and overall frame times are 11.15 in both instances
Is this normal?
The final impact depends highly on what you’re doing. What you need to keep in mind is that you render things twice.
Each eye goes through the render pipeline and for example dynamic light will be fully calculated twice making dynamic light in VR quite incredibly expensive.
It’s hard to tell what exactly is causing your performance loss but it is normal to have a significant frame rate drop when running VR.
Further, due to the effect of the lenses I also believe distorting the red, green and blue layers also cost a fair bit.