I just notice this commit on the master branch.
https://github.com/EpicGames/UnrealEngine/commit/3fe66f523e845dae5c94c96c873f86110f08cce5
What’s really cool is that it looks like there including a stencil mesh for the Rift as well.
For those that dont know the stencil mesh is a technique put forward by Valve to reduce fill rate by about 17%.
http://alex.vlachos.com/graphics/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf
If I understand this correctly what it basically does is not render parts of the scene that we can not see due to warping then warps the scene which basically gives a free performance boost?
Would something like this be possible on the mobile engine for the GearVR?
Just wanted to say Opamp, that was an awesome read, thanks for that 
Always psyched about performance gains in VR, more dynamics here we come !
Yeah, Nick Whiting talked about that at Twitch recently.
I love that there are such great optimizations coming. Already, we’ve picked up a fair amount of FPS keeping drivers and UE4 versions updated. But the Nvidia announcements, and the work Epic is doing to eek out more performance with things like this is so fantastic. It’s becoming easier to create this stuff from month to month!
Andrew
The videos even better 
@MrScratch
Your correct about the technique.
As far as gearVR is concerned I vaguely recall reading somewhere that it doesnt play well with async timewarp for some reason.
I cant remember where I read that and if its true the reason why.