I'm running Fedora 17 on a Dell Precision M6600 with an AMD Radeon HD 6900M graphics chipset. After upgrading to KDE 4.10 through the regular software update, resizing windows is suddenly very slow, and running top(1) in another terminal shows kwin consumes close to 100% CPU when resizing a sufficiently large window.

Switching focus between windows also makes kwin eat a lot of CPU, indicating kwin is redrawing the full window contents at every focus change. However, moving the windows by grabbing the title bar shows little or no CPU usage by kwin, only the X process. Kwin support information available at http://paste.kde.org/729944/.

# rpm -qf $(type -p kwin)
kde-workspace-4.10.2-4.fc17.x86_64

which window decoration are you using?

mgraesslin wrote:which window decoration are you using?

I'm using Plastik, and switching back and forth between the other decorations shows that Plastik is without any doubt the most CPU-demanding of them all. Even the more lightweight ones do not appear to be rendering as smooth as pre 4.10-kde though. Other possibly relevant information I forgot in the OP is kernel 3.8.4-102.fc17 and Catalyst drivers ver 12.10.

ok that makes sense. You are using graphics system native with plastik - bad idea. Either stop using plastik (and any other Aurorae based theme) or switch to raster, which is a good idea anyway.