Find Best Mac Apps for System Cleanup
CleanMyMac 3 is MacPaw’s catch-all utility to scan your Mac and remove gigabytes of assorted cruft and gunk that builds up over time. Like its previous versions, CleanMyMac 3 works to identify. Junk is often invisible, but it can take an enormous amount of space. Cleaning a Mac by yourself is a tiresome and laborious task. So, here's a tip: Try CleanMyMac for free and get temporary files, system.
Thorough research of cleaning and utility apps market made it possible to distinguish the top maintenance software available for Apple computers. To make the hard choice easier, you can find a review on each of the apps from the perspective of a seasoned macOS user. Besides the benefits to system maintenance for Mac that will get your slow Apple machine running buttery smooth again, part of the review is dedicated to the process of manual utility uninstallation. Following the guides inside will help you securely remove notoriously problematic cleaning apps and simplify the transition to the new application.
The reviews will also give you a general perspective on the main system cleaning features and additional utilities as well as how the app stacks up against competition. You will also discover which of the apps offer best features for the price and which provide free trials. No matter what OS X version your Mac is running — there is always an app to clean it up.
Mac's don't need defragging as OS X automatically writes 2Gb or below sized files to one contiguous space on the drive. There are certain cases where's it's needed to free up a large spaces on the drive, but not something everyone has to do.
Far as other Mac maintainence, there really isn't any except to backup one's files regularly. Keeping Software Updated and run a web browser check to make sure the plug-ins are current.
Best Mac Cleanup App
For Safari and Flash, this check is more accurate
Most of those cleaning programs are junk, especially MacKeeper.
If your friend got onto your computer and visited a bunch of adult sites, then I would recommend something like OnyX, doing ALL the cleaning and maintenance aspects and rebooting, perhaps followed by a Disk Utility Erase free space.
CCleaner beta is out for OS X, used on PC's and combines cleaning and scrubbing of the drive if setup correctly.
Clean My Mac App
If your interested in performance, read my post here