Steps to reproduce:
1. Download and open the attached project
2. Build for standalone
3. Open a hardware monitoring program (e.g HWmonitor or MSI Afterburner)
4. Run the build under OpenGl(project is set to that right now)
5. Observe CPU and GPU usage
6. Run the build under DirectX 11
7. Observe CPU and GPU usage

Expected results: relatively the same usage
Actual results: vastly different usage

Reproduced on 5.5.5f1, 5.6.3f1, 2017.1.0p2, 2017.2.0b5, 2017.3.0a2

Results on a GTX 970 i7-6700k
OpenGL: GPU usage ~90%, CPU usage ~40%
DirectX: GPU Usage ~75-80%, CPU usage ~15-20%