Thanks all for many great suggestions.

The file count has been fairly stable recently so I don't think I can learn much now by comparing two relatively current dates. I have run CCleaner several times. Perhaps the next Windows Updates will reveal something. I also uninstalled and reinstalled six updates a while back so maybe that is a factor.

The Extended Disk Cleanup looks worth trying although it looks like a little effort. I wonder if it finds files not listed by CCleaner.

The mystery is the approximate 50K file increase reported by Avira Anti-Virus. It could just be an anomaly related to how Avira scans and reports. AVG reports only 80K files scanned total.