I've been noticing lately a lot of people have been asking "Why is disk cleanup taking so long???". Some people seen to think Windows just deletes them right away or marks the file for deletion, but there is a little more involved than that, especially for kernel changes such as the updates on Patch Tuesday. Files in use must be flagged, replaced, copied, moved delayed to a temp file, written, and renamed. I'm sure many have seen this term: PendingFileRenameOperations. This must happens to all "in use" files be it drivers, windows defender, and Windows Updates it takes time to do.