Quote Originally Posted by peip
A Reiser File System is used but I think it's a problem of KDE, because when running another environment, like Windowmaker for example, the system behaves 'normally'.
Well then as aay said how much memory do you have KDE is a memory hog if it is using the swap partition a lot it has to access the HD. To check how much of the swap memory is being used open a console window and enter top it gives you a running total open and close a few apps and see if the "problem" persists.