I don't know what to say... too many new threads of pretty much already answered questions, just for starters install a task manager.
task manager is found in this thread, post number 4.
http://forum.ppcgeeks.com/showthread.php?t=114806
there is curerntly no cab i know of that will make it any faster, in my point of view is already fast
edit: not trying to sound mean but I've been posting a lot today lol since i woke up... my hands are dead tired/annoyed of typing same things over n ever so please do read in the threads out there....