To reproduce:
1. Open GraphicsPerf project;
2. Change platform to iOS;
3. Change Graphics API to Metal;
4. Build and run DynamicVBO and Objects scenes on iOS devices;
5. Change Graphics API to OpenGLES3 and build on iOS devices;
6. Compare the frame time between both Graphics APIs.

Important: please let devices to cool down between tests.

Expected result: Frame time with metal is lower than OpenGLES3.
Actual result: Frame time with Metal is 1-15% higher than OpenGLES3.

Devices under testing:
-iPad Mini 4 (SoC: A8, iOS: 11.4),
-iPhone SE (SoC: A9, iOS: 10.0.1),
-iPhone X (SoC: A11, iOS: 11.4),
-iPad 5th gen (SoC: A9, iOS: 10.3).

Reproduced with: 2018.3.0a6, 2018.3.0a7
Not reproduced with: 2018.2.1f1

Fixed in 2018.3.0a10