I noticed the huge slowdown weeks ago. Not in scanning just in opening the program. I didn't think a lot about it - I assumed it was when I updated CCleaner (I keep it updated). There have been many theories here, but here's my experience:
Dell Vostro 1500 Laptop - WinXP SP2
I recently ran into an unrelated problem and had to revert to an old image that was a year old. It's the image I call "minimal" with my mainstay apps installed (it's an apps only partition). The old CCleaner started up fast just as it always did with the old version. The FIRST thing I did was update CCleaner. I then went to open the program and - surprise! - it was very, very slow.
This tells me that the system image exactly as it was 10 months ago and updated ONLY with CCleaner gave me the --- slow CCleaner.
What does that tell me? It's something in CCleaner's latest updates. But, maybe there's another explanation. I'm really not offering a real cause or correction - just my experience.
Thanks, Piriform, for CCleaner. No matter the load speed, it's sweet.