KDE unusably slow with XGL enabled, on Mobility Radeon 9700
I have an ATI Mobility Radeon 9700 graphic card, and am using the proprietary fglrx drivers.
Problems have started when I enabled the XGL desktop acceleration, bacause my KDE has become unusably slow. At least with any window manager except Beryl (I have tried KWin, Metacity, xfwm4 and Beryl). When I start XFCE everything works fine, until I start a KDE application, such as AmaroK or Konsole, which apparently cause everything to slow down beyond use again (and when I turn the KDE application off, everything works fine again).
This all happens as long as I don't have Beryl runnig. When Beryl is on, everything works fine.
Since I'm new to Linux, can someone please tell me what additional information should I post here, and give me some leads or ideas what I should do anout this issue?