Hi everyone.

My kwin's compositing does not really run smooth and I'm looking for ways to speed it up. When I let it sit idle at the desktop, it stays at 60FPS, but when I start playing a movie in mplayer it drops to around 40FPS and the movie plays very choppy. (Fortunately kwin unredirects full-screen windows, so playing a movie in full-screen is smooth, even with compositing enabled).

The same happens when moving or resizing windows. Generally, doing anything with windows will cause the framerate to considerably drop which makes moving windows very choppy and ugly.

I can experience considerably better performance with compiz, being able to play full-screen movies smoothly even when you turn off the "Unredirect full-screen windows" option. Moving windows also looks a lot smoother than with kwin's compositing.
However, current versions of compiz don't run nicely on my system (screen goes black when you switch terminals etc.). Besides, kwin naturally integrates better with KDE (e.g. window thumbnails on the taskbar) and you can turn compositing off at any time using Alt+Shift+F12 which is quite handy sometimes.
Also, kwin did not crash once as long as I'm using it, whereas compiz tends to crash occasionally.

I have an nVidia graphics card (GeForce 9600M GS) inside an LG notebook, using the proprietary nVidia driver version 180.51.

I'm running KDE 4.2.3.

Are there any "hidden options" to make kwin run faster on nVidia cards? Can I expect performance improvements in 4.3?

Have you looked at this thread?

are you running qt4.5? if not it might help

I'm already running qt 4.5.1.

Setting those options mentioned in the other thread didn't make any noticeable difference. Besides, many options like InitialPixmapPlacement and PixmapCacheSize have pretty good default values in the newer drivers.

I disabled CPU frequency scaling. This makes at least moving windows work smoothly. It still lags when I play a movie while doing it, though. This slowdown occurs regardless of which video output I select in mplayer (xv, x11, gl, vdpau).

Running glxgears also causes an extreme slowdown, making everything jerky and unresponsive. I can't observe such a huge impact when using compiz.

Minimize and Restore also isn't smoothly animated.

Are there versions of the nVidia driver that are known to give better performance with newer cards?

you could try the 185.19 driver - here's the ftp site ftp://download.nvidia.com/XFree86/