How to reproduce:
1. Download attached project file
2. Open "Main" Scene
3. Press Play
4. Change graphic settings to "Fantastic" (in game, you can change graphic settings with PageUp button)

Actual result: Fps drops then the user sets Graphics API to OpenGLCore and turns V Sinc Count "Every V Blank" on. FPS becomes 7-15 lower (only with Editor, built game shows normal fps)

Reproduced with: 2017.1.0b8, 2017.1.1p1, 2017.2.0b11, 2017.3.0a7
Not reproduced with: 5.6.3p3, 2017.1.0b7

Regression since: 2017.1.0b8

Tested with:
Mac 10.9.5, 3.06 GHz Intel Core 2 Duo, 6GB RAM, NVIDIA GeForce 9400 (drops from 52-56 to 41-45)
Mac 10.12.3, 2.9 GHz i5, 8GB Ram, NVIDIA GeForce GT 750M (drops from ~50 to 35-42)
Mac 10.12.6, 2.3GHz i7, 16GB Ram, NVIDIA GeForce GT 750M (drops from stable 60 to 55-60)

Windows 10,7, DirectX 11, 9, OpenGLCore (not reproduced)