Windows – Why does Disk Cleanup take so much time and cpu

disk-cleanupwindowswindows 8.1windows update

Just a curiosity question. Disk Cleanup has been spending 100% of one of my cores for quite a while and still going. Seems to be spending a lot of time especially on Windows Update Cleanup.

Can't quite understand why deleting files should be such an intensive activity. Especially since it already spent quite a lot of time calculating what it could delete.

Why does Disk Cleanup take so much time and cpu? What does it do that is so intensive?

Two of four cores maxed out

Best Answer

Windows compresses the WinSxS folder by removing replaced updates ad compressing files which can't be uninstalled and which are not used into diffs. This takes a lot of CPU power and thats why you see a high CPU usage.

You can analyze the CPU usage with xperf/WPA to verify this.