Update to Latest OS X Upgrade to the latest version of OS X . If you are upgrading from Lion to Mountain Lion, then tere’s no need to visit a store and fetch a box, and install a bunch of discs. Just click the Mac App Store icon on your Mac. Buy OS X Mountain Lion. And your Mac does the rest. Clean System and User Caches etc. Using OnyX OnyX is an utility for Mac OS X which allows you to run system maintenance, to configure some hidden parameters of the Finder, Dock, QuickTime, Safari, Mail, iTunes, login window, Spotlight, and many of Apple’s applications, to delete caches, to remove a certain number of files and folders that may become cumbersome, and more.