In KDE 4.5.5 KWin synchronizes resizing operations with the rendering of widgets inside windows. In theory, this allows smoother resizing. In practice, the widgets render rather slowly on low-powered graphics chipsets, causing windows to resize in slow jerks.

Is there any way to disable synchronized resizing, preferably without recompiling KWin?

System Settings -> Window Behavior -> (Window Behavior ->) Moving -> uncheck "Display content in resizing windows". As you use 4.5 the location might differ slightly.

If you use desktop effects there's also a Resize Window effect (not sure if it's available in 4.5 though).

I think you misunderstand me...

What synchronized resizing does is forces the window frame not to resize until the widgets inside rerender. With it, the window will resize in jerks if rendering is slow; without it, the window can be freely resized as the widgets rerender, but the widgets will in fact be rerendered as the window is resized.

For instance: Openbox (as of version 3.4.11) uses synchronized resizing. If you resize a slow-rendering application in it, the window frame will lag until the application finishes rerendering itself. Blackbox OTOH does not use synchronized resizing; if you resize a window in it, the window frame and the widgets inside will both change, but they'll change independently.

(Not updating contents while resizing - implemented as wireframes in KDE - is a whole different thing. I don't use that because it leaves graphical artifacts all over the place.)

Yes seems like I misunderstood, sorry about that. In that case I don't know the answer.

'Tis okay, thanks anyway.