There in lies the problem...putting all your trust into a free piece of software doesnt come without risks as evidenced by this users experience
"I've learned this lesson the hard way. Once I ran one of these duplicate finders to clear up some duplicate files (lean = fast, right?). When I got done ALL of my shortcut files had disappeared. My desktop was blank, my start menu was blank, my quick launch was blank.
I've decided since then that duplicate files aren't that bad"
This article explains pretty well why you should leave removing duplicates unless you really know what your doing.He also goes into other less harmful ways of improving performance
including finding out where the hogs on your computer are.Maybe useful
http://ask-leo.com/is_it_safe_to_del...ate_files.html
Far safer to do a simple thing like
start/search/images and under view select arrange icons by size