Hi.
I have an issue with kwin effects on kde 4.6.5. I was on kubuntu and all was ok , but i switched to fedora , installed the nvidia driver 280 for my 8800GTS , but now when i extend a window from the taskbar , it's slow...
I feel that the expansion is done in two stages. I put the widget FPS and indeed during the expansion have a big drop in FPS. I do not know where that may come. I do not feel downward pressure on other effects, such as moving a window. I tried to disable the blur but it's the same.
Generally if I just open a single program that will not be idle, but if I kterm + firefox is already sufficient.

Thanks for your help.

Have you tried changing the application style that you are using?