>also MacOS itself is reasonably GPU-heavy OS X's window manager is optimized for fullscreen windows on top of everything else (including menu bar and the "Doc

>also MacOS itself is reasonably GPU-heavy OS X's window manager is optimized for fullscreen windows on top of everything else (including menu bar and the "Dock"): https://developer.apple.com/library/mac/documentation/GraphicsImaging/Conceptual/OpenGL-MacProgGuide/opengl_fullscreen/opengl_cgl.html https://developer.apple.com/library/mac/documentation/Graphi... I also found that even with a GPU-heavy fullscreen application, having another (smaller) window on top doesn't noticibly degrade rendering performance. It seems the window manager is doing some clever things there in regards to compositing.