How to reproduce:
1. Open attached project and change to Android platform
2. Build and Run project on Android device (Oculus VR SDK is enabled by default)
3. Observe the FPSCounter UI text or check the FPS with "adb logcat -s Unity VrApi"

Result: 2017.4.1f1 and later versions have a slight performance regression if Surface Shader is used in the scene

Regression introduced with - 2017.4.1f1
Reproducible with - 2018.2.0b2, 2018.1.0f2, 2017.4.2f2, 2017.4.1f1
Not reproducible with - 2017.4.0f1

Notes:
1. Did not experience any performance difference when VR SDK's are not used
2. Seems to happen on Daydream and Cardboard VR SDK's as well, same behaviour with Multi-Pass and Single-Pass stereo rendering methods

DUT:
Reproducible with:
Samsung SM G930F*, OS:7.0, CPU:arm64-v8a, GPU:Mali-T880, Build:samsung/heroltexx/herolte:7.0/NRD90M/G930FXXU1DQC4:user/release-keys
Samsung SM G950U*, OS:7.0, CPU:arm64-v8a, GPU:Adreno (TM) 540, Build:samsung/dreamqltesq/dreamqltesq:7.0/NRD90M/G950USQU1AQC8:user/release-keys
Google Pixel 2 XL*, OS:8.1.0, CPU:arm64-v8a, GPU:Adreno (TM) 540, Build:google/taimen/taimen:8.1.0/OPM1.171019.011/4448085:user/release-keys

Not reproducible with:
Samsung SM G950F*, OS:8.0.0, CPU:arm64-v8a, GPU:Mali-G71, Build:samsung/dreamltexx/dreamlte:8.0.0/R16NW/G950FXXU1CRB7:user/release-keys
Samsung SM G965F*, OS:8.0.0, CPU:arm64-v8a, GPU:Mali-G72, Build:samsung/star2ltexx/star2lte:8.0.0/R16NW/G965FXXU1ARB3:user/release-keys