I was worried to give this thing a shot with all the complaints about CPU usage. I have the activity monitor opened and don't see any issues at all. It's actually showing 0 CPU usage. The protect my mac feature is on. I really don't even notice it running. It's free and only gives protection for Mac viruses(which are next to non or none depending who you talk to) and I intend to keep it around. Hasn't hurt and you just never know.