Registry Cleaners

Myth - "Registry Cleaners improve performance."

Reality - "A few hundred kilobytes of unused keys and values causes no noticeable performance impact on system operation. Even if the registry was massively bloated there would be little impact on the performance of anything other than exhaustive searches." - Source

Notes - "Registry Cleaners can fix problems associated with traces of applications left behind due to incomplete uninstalls. So it seems that Registry junk is a Windows fact of life and that Registry cleaners will continue to have a place in the anal-sysadmin's tool chest, at least until we're all running .NET applications that store their per-user settings in XML files - and then of course we'll need XML cleaners.