very slow window move / resizing with catalyst

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https://bbs.archlinux.org – hello,today i set up a new arch system with a radeon 6870 gpu.i installed the proprietary catalyst driver with pacman -S catalyst-dkms catalyst-utilsthen i disabled kms ( "nomodeset" kernel option )after that i created a xorg.conf withaticonfig --initialnow the xorg server starts and the performance in flashplayer or mplayer is allright but the movement or resize of a window is insanely slow and takes 100% of the cpu (running an overclocked Core2Quad Q6600 @ 3,6 Ghz).the last hours i tried to fix that problem, but i couldnt solve it yet.i have no idea what may cause the problem, so i (HowTos)