Steps to reproduce:
1. Download and open attached project "Unity 5.3 tests.zip"
2. Make sure the API in player settings is set to OpenGLCore
3. Play the scene and notice overhead in profiler
4. Change API to OpenGl2
5. Play the scene and notice that overhead is noticeably lower with older API

Expected result: Same overhead or smaller with new API

Tested and reproduce on:
Windows 10
Unity 5.3.1p3, 5.4.0b1

Not reproducible:
Unity 5.2.4p1