2D Extreme when it was introduced in Mac OS X Tiger) is GPU acceleration for the Quartz 2D API. With QuartzGL enabled, all Quartz drawing commands are translated to OpenGL commands and executed on the GPU. This differs from Quartz Extreme, which still executes Quartz drawing commands on the CPU but performs final composition using the GPU. As of OS X Mountain Lion, QuartzGL is still not enabled by default. However, it is possible to enable it using the Quartz Debug application included in the Apple Developer Tools. QuartzGL will be disabled once again upon quitting the Quartz Debug utility. A workaround is to force quit the Quartz Debug application, which will leave QuartzGL enabled system-wide. All graphics cards capable of supporting Core Image also support QuartzGL. See also Quartz Compositing window manager X11 Wayland DXGI Desktop Window Manager References External links The Graphics and Windowing Environment - from Apple's Mac OS X Documentation Quartz Services Reference Compositing window managers Display servers MacOS user interface