Quote Originally Posted by HELL_YEAH View Post
I have the solution to that problem!!!!!! Worked perfect for me!

Go to your CONFIG file in /home/user/.quakelive/quakelive/home/baseq3/qzconfig.cfg and add that line:
seta r_enablePostProcess "0"

Do this without the home of QuakeLive opened, because sometimes it can't save the changes, so close QuakeLive, edit that file, open QuakeLive and enjoy!!

Source
It also helped me!! Thank you very much !!