Memory Cleaner monitors your memory usage and cleans up your Mac's memory, increasing performance. The application monitors RAM usage on your. Cleaner One Pro is the best computer cleaning app that helps organize and optimize disk space usage, frees up storage and manages apps on your Mac or Windows PC. AppCleaner is a small application which allows you to thoroughly uninstall unwanted apps. Installing an application distributes many files throughout your System using space of your Hard Drive unnecessarily. AppCleaner finds all these small files and safely deletes them. Overall, Macgo iPhone Cleaner for Mac will clean out most junk files. It has customized app cleaning settings, so you can tweak it for what you need, and the app is compatible with the latest version of iOS; iOS 8.3. Macgo iPhone Cleaner for Mac run on Mac OS X 10.8 or above and is compatible with iPhone, iPad, iPod touch (iOS 5-8). Beneath its deceptively simple design lies a powerful virus cleaner that works in real-time to detect and remove not only Mac-specific viruses and spyware, but PC and mobile threats, too. So AVG AntiVirus not only helps protect all that’s important on your Mac, it also prevents you from infecting friends on.
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.
Cleaners For Mac Computers
Rar for mac software. For Safari and Flash, this check is more accurate
Best Computer Cleaners For Mac
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.
If your interested in performance, read my post here