If there is something I really expect out of today’s computer, it is performance.

I’ve been a KDE4 user since the version 4.3 and there are a lot of performance improvements to be made. As I usually like bleeding edge/unstable (call it the way you prefer) software,

As it is super easy on ArchLinux, I have been testing kde 4.6 since the beta 1’s release. Apart from some graphical glitches, I was very pleased with it, especially from a performance point of view.

And then came the Release Candidate 1. The system became unresponsive as the performance dropped to an insanely poor level!

MaxFPS set to 35 instead of 60

First of all, the FPS rate dropped from 100 fps to 35. It appears that some smart devs thought that would free up to resources (and made animations look like bullcrap!). While I agree 100 fps was too much, I would have considered having a maximum fps rate set to the screen’s refresh rate (ie. 60fps on most computers now).
You can fix this by editing the kwin configuration file:

$EDITOR ~/.kde4/share/config/kwinrc
...
[Compositing]
MaxFPS=60
...

Use the Qt’s built-in raster engine

I will quote Zack Rusin (from VMWare). Please read his blogpost called More 2D in KDE (you may want to read all his blog as some articles he writes are truly amazing!).

If you’re convinced you should use (or try) the raster engine, the simplest way is to add this line to /etc/profile:

export QT_GRAPHICSSYSTEM=raster

This should give a nice performance boost :)

LIBGL_ALWAYS_INDIRECT?

Some people also need to use indirect rendering to get more performance :o! As I am too lazy to explain what it is, here is a nice link What does LIBGL_ALWAYS_INDIRECT=1 actually do?.

If you want to give it a try, add this line to /etc/profile:

export LIBGL_ALWAYS_INDIRECT=1

Conclusion

Following those steps (but not LIBGL_ALWAYS_INDIRECT) lead me to a tremendous performance/experience improvement.

My KDE is now snappier than ever. Point #1 is a shame IMO, why the hell one would want 35fps on his desktop!? This is insane!