Clean Master - Some users swear by it, some call it a glorified snake oil that does more harm than good. That can be said about any snake oil, but what specific brand of snake oil can boast almost a billion downloads around the world?
CCleaner - CCleaner cleans, speeds up and frees up space on business endpoints.
BleachBit - When your computer is getting full, BleachBit quickly frees disk space.
Recuva - Accidentally deleted an important file? Lost files after a computer crash?
AVG PC TuneUp - Peak performance for your PC. Keeps it going for longer. - More Speed Turbo Mode
Auslogics BoostSpeed - Auslogics BoostSpeed: Tune up Your PC for Peak Performance! . * Free trial lets you clean out junk files, enable several Live Speedup tools and run each of the 18 apps under All Tools once.