Should you be using a Radeon graphics card with the AMD Catalyst Linux driver and are disappointed by the poor performance, there is a very easy workaround for gaining much better performance under Linux... In some cases a simple tweak will yield around 40% better performance!
Like Catalyst for Windows, Catalyst for Linux also makes use of application profiles for managing any per-game optimizations or workarounds for addressing driver bugs, etc. On Windows, AMD routinely even puts out hot-fix releases or special drivers that are "optimized" for major new AAA game releases. Most often these application profiles just result in the game/application running a few percent faster or to just workaround incorrect visuals. The concept of per-game/app profiles by graphics drivers is nothing new and is even similarly supported by the open-source Mesa drivers in rare cases when needing to workaround buggy software, override the exposure of certain OpenGL/GLSL capabilities, etc. Application profiles have been within the Catalyst Linux driver for years, but unlike Windows, these profiles aren't apparently maintained worth squat and is part of the reason why at least some Steam games struggle under Linux with Catalyst.
The latest example of troubles within the Catalyst driver for Linux gamers is over Counter-Strike: Global Offensive performance. CS:GO has been out for Linux since last year but Catalyst on Linux still doesn't make any checks for this popular Valve Linux game. The CS:GO AMD Linux performance was poor last year and it remains bad to this day when comparing the results to the NVIDIA Linux driver and their graphics cards. However, it turns out that there is a workaround that could be rather easily applied by the driver.