If your KDE apps feel slow and sluggish (which is most likely the case if you are using an Nvidia card) I can really recommend to change Qt's graphics system.

I'm using an Nvidia GeForce 9800 GTX and KDE runs so much faster when using the Raster backend rather than the supposedly "hardware-accelerated" Native backend.

For example, try scrolling in dolphin. Open a folder with a lot of files, then drag the scroll bar handle (it's especially slow in the "Details" view mode).
Quit dolphin (!) then open konsole and start dolphin with "dolphin -graphicssystem raster". Now, try the same thing again. It's awesome, isn't it?
You should also try resizing the window!

Here is a KDE Control Module that can change the default graphics system for you: http://kde-apps.org/content/show.php/KCM+Qt+Graphics+System?content=129817

Note that you need at least Qt 4.7 to be able to change the graphics system.

You can also manually create a script file in ~/.kde4/env. Name it e.g. "qt-graphicssystem.sh" (or something else) and paste this into it:

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export QT_GRAPHICSSYSTEM=raster

You have to log out and log in again for changes to take effect.

Now, enjoy your lightning-fast KDE. (Okay, it's still slow compared to 3.5, but...)

Interesting - have you tried the openGL backend? though old this article implies it is much faster http://labs.qt.nokia.com/2008/10/22/so- ... -the-blit/

update - tried openGL backend and nothing but issues - errors when starting kde (print server and another), errors when changing workspace appearance (a kde window popups on bottom left with no text), screen filled with tiny dots, plasma not showing icons on taskbar.

Went back to default (from raster) as some icons (notifier, krunner toolbar) not showing - of course ymmv

Hmm..yes raster makes everything runs smooth, but since I activated it the fan of my 7600GT is running all the time which is very annoying. Anything I can do about that?

Open Office doesn't work on KDE with Raster

Well, you can remove the openoffice-kde package but Open Office applications will look so ugly without KDE integration.

Does anyone know, why this problem occurs with the nvidia driver? Did they not implement something from the 2D acceleration in X, or...?

Thanks, superori, that fixes the openoffice crashes I have been having. Is there a way to disable raster graphics just for openoffice?

Should work if you either start Open Office from a console window or edit your Open Office button. Use this command:

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QT_GRAPHICSSYSTEM=native ooffice

The fan speed problem is very strange. Did you open nvidia-settings and check your performance settings and temperature?

This helped out A LOT, apps do seem to crash a little more often, worth the speed boost though. Does anyone have an idea to automatically have all gtk apps use the native qt rendering? Raster breaks gtk-qt style (open office uses that I am pretty sure) which I like very much.

[edit]
sorry did not mean to bump this...

You can make certain apps automatically use the native rendering by editing them in the menu editor.

Right click on the KDE menu and then select 'Menu Editor'. Select the app you want to use native rendering with and append to the start of the command entry:

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QT_GRAPHICSSYSTEM=native

so that for open office writer the command looks like this:

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QT_GRAPHICSSYSTEM=native oowriter %U

Hope that helps

amas wrote:You can make certain apps automatically use the native rendering by editing them in the menu editor.

Right click on the KDE menu and then select 'Menu Editor'. Select the app you want to use native rendering with and append to the start of the command entry:

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QT_GRAPHICSSYSTEM=native

so that for open office writer the command looks like this:

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QT_GRAPHICSSYSTEM=native oowriter %U

Hope that helps

I actually found oxygen-gtk (http://gitorious.org/oxygen-gtk) which fixed my problem. It looks way better then qt-gtk, and is fine with me using raster.

Can you explain exactly what you did to get this working?

The raster engine makes no discernible difference when using QtCurve, but makes a huge impact on the performance of the Oxygen theme. I read somewhere that Oxygen uses some graphics features that the NVIDIA binary driver is terribly slow at.

My solution: use the QtCurve theme engine instead of Oxygen. It is much faster than Oxygen on NVIDIA, and you won't have the glitches and problems that show up with the raster drawing mode. Here's a nice QtCurve theme to start off with:
http://kde-look.org/content/show.php/CurveDomina+Qtcurve?content=126954

TheBlackCat wrote:Is there a way to disable raster graphics just for openoffice?

Try adding the following to the file /usr/lib/ooo-3.3/program/soffice (or /usr/bin/soffice that symlinks to it):

QT_GRAPHICSSYSTEM=native
export QT_GRAPHICSSYSTEM

Depending on your distro libre/openoffice could be installed in another prefix e.g /opt.

Oxygen went from being slow to being very very snappy on my 9800. Thank you so much!