It's important to run a basic cleaner every time you shut the computer down, for this i use CCleaner, also a free program, it cleans out the junk and clutter left behind by adverts and so on .
It also has a handy registry cleaner, this gets rid of dead links and so speeds the computer up .
I defrag weekly too .
Both these free programs are available in file hippo.com :
https://www.google.com/search?client=firefox-b-1-d&q=filehippo+ccleaner