"Disk fragmentation is generally main cause of slow and unstable PC performance. IObit SmartDefrag helps defrag your hard drive most efficiently. With "Install it and forget it" feature, IObit SmartDefrag works automatically and quietly in the background on your PC, keeping your hard disk running at its speediest. Slow down, freeze-ups and crashes will be a thing of the past. IObit SmartDefrag is 100% free for personal, home and small business. Detected by many strictest tests, IObit SmartDefrag is 100% safe and has no spyware/adware. "