Its always been slow to start, but now its slow cleaning too, at least in Windows and Applications,but the Registry part is fine though.
We don't know your ccleaner settings (such as multiple wipe) what you have checked off on both system and applications tab or much else about your particular situation (like at what point slowness happens and whether any browsers or apps are open while ccleaner tries to clean)
Edit
Also slowness to start is usually indicative of have a overly large winapp2 file (or running any ccleaner enhancing software). Please confirm/refute such usage and if confirming remove said item (at least temporarily) before we can continue to aid you