Memory Clean is the ultimate app for optimizing your Mac's memory and is best used after you have finished using a memory (RAM) intensive app or game. With the slickest interface and user experience, Memory Clean stands head and shoulders above the rest. Note: Memory Clean works by purging the Mac's inactive memory and is best used when you close an intensive app that you do not plan to use again quickly within a few hours. During the cleaning process, older Macs may slow down until the cleaning is complete.