Please refer to the FAQ ' Windows 10 - Increase the free space on your OS drive with Disk Cleanup' for more information about Windows Disk Cleanup. Because that’s presumably why you are running the Disk Cleanup tool.More Discussion About Windows Disk Cleanup as well as the Windows 'Free Up Space' Tool And that’s the cost: You need to spend a lot of CPU time to do the compression, which is why the Windows Update Cleanup is using so much CPU time.Īnd it’s doing the expensive data compression because it’s trying very hard to free up disk space. The compression algorithm used by the Windows Overlay Filter is higher quality than a real-time compression algorithm, and it’s designed so that decompression is fast, but compression is expensive. If so, then it takes the operating system files that aren’t already compressed and compresses them, storing the result in the WofCompressedData alternate data stream, as I described some time ago. The other thing that the Windows Update Cleanup task does is check with the WofShouldCompressBinaries function to see whether the system would benefit from compression of system files. I suspect it’s there just as a backstop in case the scavenging process goes haywire.)

(I don’t know if the one hour timeout is actually meaningful in practice. Unreferenced components are removed immediately, and the task will run to completion, even if it takes more than an hour. But the special command line above bypasses both the 30-day grace period and the 1-hour timeout. The automatic scavenging has a policy of waiting 30 days before removing an unreferenced component, and it also has a self-imposed time limit of one hour. Normally, the system automatically does component scavenging on a schedule maintenance task. This is a command that goes by the nickname deep clean, and it scavenges the component catalog looking for components that are no longer being referenced.

It’s basically doing two things.įirst, it does the equivalent of dism /Online /Cleanup-Image /StartComponentCleanup. The Windows Update Cleanup option is doing more than just deleting files. What the heck is it doing? How hard can deleting files be? If you ask the Disk Cleanup tool to clean up Windows Update files, you may find that it takes a long time and consumes a lot of CPU.

Running disk cleanup