This instruction is a work in progress. Do not go through with it unless you feel confident you can fix any problems you run into. I would appreciate peer-review from any Ubuntu community member.
So, you like KDE because its configurable or is well integrated, but your slow computer doesn't handle it very well. Or you are annoyed by strigi slowing down the system all the time, but don't want to disable it. Or you just want to have a fast desktop. Why is KDE so slow, you wonder?
The big problem is that KDE makes many, many reads and writes to ~/.kde, the location of all of the major KDE related files. Analysis indicates that Konqueror makes as many as 40 reads and writes when loading a webpage! We can greatly speed this up by putting all that data, not on the disk, but on the ram. If you have 500MB or more of ram, or you regularly have at least 100MB free, you can mount ~/.kde on a "ramdisk", a fake file system mounted on the ram.
This seems to speed up kde a lot for me. In particular, if an application makes heavy disk reads or writes in the background (like strigi), my system is still nice and fast. My solution will somewhat slow down the initial booting process, but it will speed up logging into KDE.
This only works for KDE 3. I will update it for KDE 4.
A disclaimer: it is possible to break your system with this. If you back up ~/.kde like I tell you, you will be able to recover. Be careful.
Get a copy of the scripts (kderamdisk02.tar.gz). Extract them and run "Run-me.sh" in a terminal. Follow the onscreen instructions.
...is always appreciated, even negative feedback. If I messed up your system, I'll try to take responsibility and try to fix it. You can reach me at ConorWSullivan@gmail.com