Microsoft claims Longhorn will be, er, faster
The only reason why its faster is they added a superfetch feature to the prefetcher. If you look at the key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\Prefetcher
you will notice in windows xp
EnablePrefetcher = 3 and you will notice in windows longhorn
EnableSuperfetch = 1
Well, guess what? You can put the EnableSuperfetch = 1 in windows xp and get the same speed.
Wow, Microsoft just added a feature that was already there in xp.
Make sure after you make the new DWORD to set it too 1.
USE AT YOUR OWN RISK
Don't forget to reboot for the tweak to be applied.
I've just done the above and after the first load there does appear to be speed increase.
If your unsure how to edit the registry copy the following into notepad call it update.reg then right click on the file you have just saved and click merge.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters]