Here's some info from Ursamajoran at ExtremeTech. Looks interesting in concept, but I experienced a big problem with Fookes Software's NoteTab Lite after these hacks. Saving to an NT4 share hung the application and corrupted the edited files. Use at your own risk...
One thing you can do to speed up Windows XP is to make sure that key operating system functions stay in memory. Memory (also called "RAM") is much faster than the hard disk. Perform the following steps to pep up your XP computer's performance:
Click the Start button. Click the Run command and type regedit in the Open text box. Click OK. As always, be very careful when editing the Registry.
In the Registry Editor, go to the following registry key:
HKEY LOCAL MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
Right click the DisablePagingExecutive entry in the right pane of the Registry editor and click Modify.
In the Edit DWORD Value dialog box, type the number "1" (without the quotes) in the Value data field. Click OK.
Right click the LargeSystemCache- double click it and change the decimal to 1 -this allows XP Kernel to Run in memory improves system performance alot
Close the Registry Editor and restart the computer.
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).
It should decrease the boot time and the time it takes to load programs.