Steps to reproduce:
1) Open the attached project (Maya *might* be needed to import all the models).
2) Build for iOS.
3) Deploy on a device.
4) In Xcode's debug FPS section, monitor GPU Frame Time.

Test results on some devices (5.5.1p3 | 2017.1.0b3):
iPad Mini 4 iOS 9.3.2 - 27 ms (37 FPS) | 47 ms (21 FPS)
iPhone 7 Plus iOS 10.3.1 - 13,2 ms | 14,7 ms (both capped at 60 FPS)
iPhone 6 Plus iOS 8.0 - 22,5 ms (44 FPS) | 157 ms (6 FPS)

Some devices (like the iPhone 6 Plus above) are suffering particularly big FPS drops. Disabling MSAA or switching the Graphics API to OpenGL ES reduces GPU frame times to normal.

Reproduced on:
2017.1.0b3, 5.6.0f3

Did not reproduce:
5.5.1p3