Foundation of tweaking

Much like building a house, the foundation is important. Tweaking and optimizing KDE will mean little in actual performance gains if the foundation is improperly laid.

1. Probably the first area users should focus is the distro they select. Some distro vendors try to be all things to all people and that effort results in a lot of unnecessary complication and overhead. This is especially true with distros where the vendor tries to merge several GUIs into a seamless operation. Doable, for sure, but clunky and slow. If users have decided to use KDE as their primary GUI, then select a distro that does not use the all-for-all approach.
2. Along with the distro choice, use the 2.6 kernel rather than the 2.4. This is rather standard these days, but there is a noticeable difference in speed between the two kernels.
3. Another area where users should focus is underneath the GUI: the X server environment. That is, users should ensure that X is configured correctly and there are no errors in the X server boot log (typically located at /var/log/Xorg.0.log).
4. Ensure the correct X driver is installed for the video card. The generic VESA driver will not run as quickly or efficiently as dedicated drivers.
5. Select a screen resolution that your system will handle easily. Although larger monitors handle screen resolutions of 1280x1024 and higher, some people might be content at 1024x768.
6. A similar X tweak is to run the video resolution at a lower screen depth. Many people with new hardware assume that everybody needs to run their boxes at 24-bit (16,777,216 colors) depth. Not so. To improve video response, consider running X at a 15-bit (32,768 colors) or 16-bit (65,536 colors) depth. Note: KDE provides no direct way to reduce color depth—manually edit the /etc/X11/xorg.conf file.
7. Related to configuring X is ensuring there are no problems with fonts. Inspect the X server boot log for clues. KDE uses font caches, therefore the number of fonts installed should not impact performance in any dramatic manner. However, ensure all font directories contain a font cache file.
8. If the budget allows, buy additional RAM. The Linux kernel tends to be RAM intensive rather than CPU intensive. Most older Pentium Socket-7 motherboard (Pentium I and MMX) will support up to 256 MB of RAM. Adding RAM will improve performance noticeably, even with older motherboards.
9. If the budget allows, obtain a newer hard drive. Bear in mind that the BIOS of older motherboards will limit the size and speed of the hard drive. However, used 20 and 40 GB drives manufactured only a few years ago are available for far less than one pays for new drives and need not impact the budget deeply. These drives minimally are ATA-33 and use DMA (direct memory access). Except for hobbyists and certain dedicated applications, many typical desktop users will never fill a 20 GB drive to capacity. Important, however is that the drive should support DMA.
10. Enable DMA. DMA will improve performance noticeably. For some distros, this option might require adding some lines to the startup rc.local script using the hdparm command.

Tweaking KDE

After establishing these foundations, users can tweak KDE to perform well on older hardware. Several options are listed at the KDE wiki.

1. Update to a recent version of KDE. The updating game gets old real fast, but generally, with KDE a recent version means improved performance.
2. Disable wallpaper. Select a pleasing and comfortable desktop screen color. (Configure Desktop.)
3. Disable background gradients. (Configure Desktop.)
4. Disable shadowed fonts. (Configure Desktop, Advanced Options.)
5. Disable desktop icon tool tips. (Configure Desktop, Behavior.)
6. Minimize the number of device icons on the desktop. (Configure Desktop, Behavior.)
7. Virtual desktops. Limit this to two desktops, possibly only one. Consider that most people are not multi-taskers. Typically most people concurrently run only two to three desktop programs. Having a bunch of programs running in standby, which is how virtual desktops basically work, means a lot of extra overhead that most typical users do not need. Although useful, many people get by comfortably with only one desktop. (Configure Desktop, Multiple Desktops.)
8. Use a plain blank screen saver. (Configure Desktop, Screen Saver.)
9. Disable the mouse cursor launch feedback. (Appearance and Themes, Launch Behavior.)
10. Disable themes. Yes, themes add a degree of personalization, but with older hardware, at the sacrifice of speed and response.
11. Consider using the KDE Classic widget set and KDE 2 window decorations. Yes, this ends up looking like MS Windows 95, but this desktop is easy on system resources. (Appearance and Themes, Style; Appearance and Themes, Window Decorations.)
12. Disable displaying window content when moving or resizing windows. (Desktop, Windows Behavior.)
13. Disable shading animation and hovering. (Desktop, Window Behavior.)
14. Disable transparent and translucent menus and panels. These bells and whistles are CPU and memory intensive. (Desktop, Window Behavior.)
15. Disable GUI effects, such as cascading menus and drop shadows.
16. Mouse cursor. A simple non-themed mouse pointer is sufficient for most people.
17. System sounds. Reduce the number of system sounds being used and use sound files that are small in size and load quickly.
18. Enable Konqueror preloading. Konqueror will load faster and Konqueror is too useful as a file manager not to have this option enabled. (Control Center→KDE Components→KDE Performance)
19. Disable as many KDE specific services as practical. (Control Center→KDE Components→Service Manager)

Hopefully these suggestions will noticeably improve your KDE performance with your older box.