Windows XP contains a directory known as Prefetch in which it stores files that are used to start Windows XP and other applications. By prefetching, Windows XP can read ahead into the cache the data that is expected to be requested (remember it’s much faster to read data from the cache). You can see overall how this prefetching can improve performance.

Over time some of the files within the Prefetch directory are no longer used. The result is that it can noticeably slow down your computer’s boot time. So what can you do? Open the run command and type is Prefetch. This takes you to the Windows\Prefetch directory. Once you are there, delete all the files within the folder (or at least those files that are more then two - three weeks old).

A word of caution, empty this directory too often can have negative results. Shoot for about once a month and you should be okay.