If you’re a KDE Ubuntu user (Kubuntu) you might not know that the standard readahead package (which attempts to speed up boot by preloading the kernel file cache by efficiently reading them in advance) is tuned for the Gnome version of Ubuntu and so will be trying to read a bunch of libraries that are probably not installed on your system. So it’s unlikely to do much for your average KDE user!
However, if when you boot you go into the Grub boot loader and add the “profile” option to the end of your command line (after “quiet” for instance) then it will profile the files used during the startup and create new files in /etc/readahead so that next time you start you’ll actually be preloading the files that will be used on your system. I’ve found it’s shaved over 2.5 seconds off my boot time as recorded by bootchart.
There is a bug in Launchpad for this, it’s 369506 but it hasn’t had a lot of love. 🙁