This is an unique technique for XP, which could improve the performance significantly by tweaking the prefetcher (which is a cache folder).

1. run "regedit";
2. goto [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters\EnablePrefetcher];
3. Set the value to either 0-Disable, 1-App launch prefetch, 2-Boot Prefetch, 3-Both ("3" is recommended).
4. reboot.

It should decrease the boot time and the time it takes to load programs.