The May 2012 Open-Source Radeon Graphics Showdown

The Catalyst driver continues to slaughter the open-source drivers for all of the GPUs, regardless of being low-end or high-end GPUs. Even the very-slow Radeon HD 6450 was more than four times faster with Catalyst. Another difference worth noting between the open and closed-source drivers is that with the Mesa/Gallium3D code there is only OpenGL 2.1/3.0 support where as the Catalyst blob provides OpenGL 4.2.