I don't think you can defrag a mac just like on a windows computer. I have never done that. I have repaired permissions, cleared cache, history but that is about it. I haven't ever really had any need to defrag after I did the above. Welcome to the world of macs. It is alot easier than windows. Trust me on this. I have had mine for over a year and have never regretted it. My only regret is having to use windows at work.🙄