I have my Lightroom catalog configured to write metadata (including keywords) to XMP files. Some keywords are used on thousands of files. It's very easy to accidentally drag a keyword to a new parent in the keyword hierachy list. When that happens, the system goes crazy applying the update to every file that uses that keyword. As soon as the keyword lands under the new parent keyword, my CPU utilization goes through the roof. When I hear the fan going full speed, I realize that I accidentally moved another keyword. There is no way to abort this operation, the updates are proceed regardless of how long it takes. Even if you quickly move the keyword back to it's proper location in the hierarchy it can take hours for Lightroom to complete all of the unwanted updates to XMP files. If you try to close Lightroom it doesn't help because Lightroom just resumes the update process the next time you start it up. In addition to the inconvenience of having these run-away updates, I am concerned about possibly damaging a file.
Please provide a warning message when keywords are dragged to a new location in the keyword hierarchy so I can cancel the keyword change and avoid needless out-of-control updates to thousands of files.