Microsoft recently updated its disk cleanup tool to also remove unnecessary Windows Updates after they are superseded by newer updates. This is quite useful on systems which haven't had a clean install in some time (like mine). I just ran it and it found 2.03GB of unnecessary files, could be useful for those with smaller capacity drives.
Same here, recovered 2gb running the disk cleanup. They've added another category to the delete choices that deals with the old updates. It retains the latest ones. This created several thousand file fragments. Defragging the C drive returned additional resources.
I think this change holds true for Win 8.1. I'm not sure, but it seems like there is an extra item to select for deletion and it has something to do with updates.