I'm wondering if I'm going to be sorry or not, but so far my computer is lightning fast because of a commercial I saw on TV for pcmatic. It's from PC Pitstop and is supposed to make your computer run faster by cleaning up stuff that you've mysteriously collected, like unwanted files & cookies and it's FREE. There was a list of stuff it was supposed to clean up and tweek, and whether it did it or not I really don't know. All I know is that it did improve the speed of my laptop, and I'm really impressed.
I'll let you know later if it was a harmful program to download and use.