The phone should run perfectly fine almost indefinitely without needing any attention. If it won't you have a problem. It shouldn't be necessary to run CCleaner. That is just slapping a temporary Band-Aid on the problem, not solving it. What you should be doing is finding what is causing the phone to slow down and correct it. You're treating the symptoms, not curing the illness.
To understand why, read the link in my previous post. Excellent info there. Here's another link to a long thread that's a treasure trove of information:
http://androidforums.com/threads/put...e-like.896663/