CC Cleaner, Adavaned System Care, AdAware and Spybot.

All free.

Give them all a run, with nothing running in the back ground.

Use the "tools" in your brouser to do a clean from time to time.

Malwarebites is a free mal remover that you only need to turn on when doing a clean so as not to conflict with your antivirous. I use Avast.

I downloaded CC Cleaner for a fella's computer and he had 8gb of junk in his registry!

Can't guarantee it's what's your problem, but it will do a needed clean. I only turn on the defrag in Advanced System Care from time to time. As it takes quite awhile.