VR Instanced Stereo
Instanced Stereo Rendering was introduced to help lessen the performance impact of VR in UE4. The feature can be enabled by checking the Instanced Stereo option that can be found under Edit > Project Settings > Rendering > VR.
After Instanced Stereo rendering has been enabled, it will require an engine restart, and shader recompile.
The base pass, and early-z pass, works with static meshes, skeletal meshes, sprite particles, and mesh particles with the feature turned on (both serial and parallel rendering paths).
Instanced Stereo currently works on PC (DirectX) and PS4 with support for other platforms coming after the initial 4.11 release.
Here is a video showing Standard Stereo Rendering in VR, versus Instanced Stereo Rendering in VR.