Originally saw this suggested for fixing stuttering issues in Saints Row 2, but apparently it works for other some other games, especially those that originated on the 360.

Taken from: http://forums.steampowered.com/forums/showthread.php?t=1715922 , and then I found out that it's worked for a few other games which originated on the XBox 360.

"* Delete the contents of c:\windows\prefetch\
This will remove all the .pf files for all apps that Windows has learned and created over time. By doing so, Windows will no longer prefetch them into memory until it relearns that behavior.
* Reboot
* Make sure you have all other unnecessary applications and processes closed/ended like web browsers, background tasks, etc.
* Run Saints Row 2 and check the prefetch folder to make sure Windows created SR2_PC.EXE[SOME#s].pf"

Obviously, in the last step, you're going to be running Raiden instead of SR2 ;)

Do note that this might temporarily reduce system performance until it rebuilds the other prefetch stuff.

Also you might need to disable prefetching before you clear out the folder to stop it from, er, putting stuff back in the folder and then restarting it after you restart your system.