More and more games are published for Linux and so it’s becoming more important to have a good performance with our beloved system, but some of the Desktop Environemnts can really slow down your gaming experience.
There is an interesting report about this on Phoronix in the article: Gaming/Graphics Performance On Unity, GNOME, KDE, Xfce, and these are their conclusions:
Overall the results were interesting from the range of Linux OpenGL benchmarks conducted under Unity, Unity 2D, GNOME Shell, GNOME Classic, KDE Plasma, and Xfce on Ubuntu 12.04. There are some exceptions, but across the driver configurations the desktops to commonly perform the best were Xfce 4.8 and GNOME Shell 3.2.2.1. The default Unity desktop was a mix in terms of performance across the different OpenGL workloads.
So there are good chance that you can speed up your graphics performance, how ? Use Fsgamer