Warning

I do not suggest running BETA quality software (especially drivers) on any system. This page merely describes what I did to my system and how it worked out - don't expect the same and don't blame me if your system crashes.

The problem

KDE4's performance on newer NVIDIA cards of the 8xxx and 9xxx series is currently pretty choppy. For as long as I've been trying running KDE4 I had to fight an unresponsive plasma and some windows that just wouldn't resize with more than 0.5 fps.

The remedy

Lately I've been reading up on a thread on the NVIDIA forums. I found out that performance can be increased dramatically by doing the following:

Install the latest NVIDIA graphics driver (173.14.09 works fine for me)
Make sure you the NVIDIA kernel module gets loaded by either rebooting or rmmod/modprobe (Of course you'll also have to restart xorg)

Set the following options:

$ nvidia-settings -a InitialPixmapPlacement=2 -a GlyphCache=1

If you're lucky your KDE4 will be snappier than ever. If you're unlucky and it stays the same or gets even worse, try experimenting with the value of InitialPixmapPlacement, setting it to 1 or 3.

Apart from that I had to play around with the Advanced Effects settings as kwin's performance seemed to have dropped.

Making it permanent

Note

While I saw this setting in someone's xorg.conf I couldn't actually make it work for me. Hints welcome!

Driver options set using the nvidia-settings tool reset back to default as soon as your xserver exits. To make it permanent you can add the options to the Device section of your xorg.conf:

...

Section "Device"
    ...
    Option  "InitialPixmapPlacement"    "2"
    Option  "GlyphCache"                "1"
    ...
EndSection "Device"

...

Experiences

Here I'd like to collect some information about the circumstances this setup will work better in. Please post your experiences to the table below:

Name	Card	Kernel	Version	I.P.P.	G.C.	Improvement
Lemma	8600 GTS	2.6.25	177.13 (beta)	2	1	huge
Lemma	8600 GTS	2.6.25	173.14.09 (stable)	2	1	huge
Teo	Quadro NVS 140M (same chip as 8400M)	2.6.25	173.14.09 (stable)	2	1	small
ehamberg	8400GS	2.6.25	173.14.09 (stable)	2	1	huge
Brandon	8800GTS 640mb	2.6.26	173.14.09 (stable)	2	1	huge(not a lot when resizing windows but scrolling in the folderview is smooth now)
friedreich	8800GTS 640mb	2.6.25.9-2-pae	173.14.09 (stable)	2	1	huge (after playing with advanced compositing options absolutely smooth (opengl, texture from pixmap, trilinear, direct rendering), keep thumbnails of hidden windows), still dogslow when adding widgets and doing animations the 1st time, putting the lines into xorg.conf doesn't work
Johannes Köster	Geforce 8600GT	2.6.25-debian	173.14.09	2	1	rather big, but only if I use shared memory as opengl mode. texture from pixmap causes long hangs every few minutes.
rivo	9600GT	2.6.22 (Gutsy)	173.14.09	2	1	huge. Plasma is now actually usable (was very painful before). KWin is also very smooth now.

I.P.P. = InitialPixmapPlacement
G.C. = GlyphCache

Known problems

I haven't done a lot of testing using this setup, so in case you encounter any unwanted effects (on 3D applications or other 2D applications), please put them below.

Following those steps with cards from the 7xxx series is said to increase GPU temperature a lot. [1]
On changing kwin's effects settings might not be possible because on applying the changes X might freeze for a period of time longer than the 10 seconds you have to confirm the change.