When using rendering effects (like Graphics.Blit) on iPhone 7 and 7 Plus, the GPU frame time becomes extremely long. This doesn't occur with other devices.

Steps to reproduce:
1) Open the attached project.
2) Build for iOS with any Graphics API.
3) Deploy to a device via Xcode.
4) Go to Xcode's Debug menu.
5) Capture GPU frame (camera icon).

A single GPU frame takes around 165 ms. Rendering of "Hidden/Internal-GUITexture" takes around 96 ms, "Hidden/BlitCopy" takes 48 ms and "Standard" 24 ms. These numbers are significantly lower on other devices (around 6 ms per GPU frame).

Reproduced on:
5.5.0b5, 5.4.1p3, 5.3.6p6, 5.2.4f1

Devices:
iPhone 7/iPhone 7 Plus iOS 10 - reproduced
iPad Mini 2 iOS 10 - did not reproduce