My MacBook Pro is running EXTREMELY slow. It just started yesterday and I am not sure why. My boyfriends little sister has been on it a lot lately and downloading an ungodly amount of junk. I go through and delete everything she has downloaded once I get my laptop back, but now it is just ridiculously slow. I know my macbook is old, but is pretty much in fantastic condition. Anyone know how I can get it running faster? I was under the impression that I didn't need a Virus blocker, or whatever those are called. Could I have a Virus?