Unknown lag cause?

Well my computer was hacked/crashed about a week ago. The other day I did a system reset from a snapshot done about a month ago. But now whenever i get on the Runescape and Call Of Duty about every 30 seconds I get 5 seconds or so of lag. This really is pissing me off. Do you have any ideas or ways I could check where this lag is coming from?

 

press Ctrl-alt delete and see what ur running and turn off program like limewire and other BIG programs that u have runnnin

 

I have no other programs running but under the performance tab in Windows tasks manager the CPU usage graph thing will be at like 2% then jump to like 100% then back down to like 7%, not sure if this has anything to due with the lagg just thought it might help

 

do control alt delete, go to processes to check what is taking up alot of cpu. click mem usage untill it goes from most memory used to least memory used and you can either end the process, or just check to see what it is.

(usually i end explorer.exe, aim.exe, limewire.exe, and bittorrent.exe, and my lag gets pretty much cleared up completely )
( you probably shouldnt end programs that you dont know what the result in ending it will be )
hope that helps.