I have the following problem with kwin: After loging into KDE everything is running smooth with compositing enabled. But after a while the systems becomes really slow (framerate drops from ~58 fps to ~2 fps). The CPU usage stays idle for the whole time. I suspect that there is something going wrong in the driver. At least I don't see this behavior with r600g.

Can anybody give me some hints how to find out if this really is a driver problem?

Best regards