Some people say KDE4 rendering speed is slow when using Nvidia cards. I never felt this so I never bothered in applying the proposed solutions. Using firefox (note: this test does not run in konqueror) simply access the penroseTitling test page and run both tests. My first tests are in the image above and as you can see not bad as I have read in the Internet that for some people the Canvas test can take up to 30 seconds while it took 3 seconds on my machine.
Anyway I tried one of the solutions that is simply running this command in the konsole:
nvidia-settings -a InitialPixmapPlacement=2 -a GlyphCache=1
And here are the new times:
Wow this is a real improvement so now I have a kde startup script that calls this command when KDE starts:
nvidia-settings -a InitialPixmapPlacement=2 -a GlyphCache=1 &