While speaking about CCleaner, I (and not only I) do not recommend using it for registry cleaning. Other features are OK.
Please see the following:
Registry Cleaner/Optimizer advice and warning!
Looks like there's this kind of software installed on your machine. I really doubt it will speed up your machine's performance, but it will surely increase the risk to damage it. Without even the basic Registry knowledge, this type of application may bring more harm than good. There were cases when such software left PC's unstable and unbootable. Below you can find Microsoft statement and some wise people talking about Registry Cleaners and this kind of Windows tweaking:
Microsoft policy for the use of registry cleaners
Mike Russinovich (Microsoft)
In your own interest should be staying away from this kind of applications.
Stay safe & you are most welcome