Any time you add, change, delete files, the index needs to be updated.spotlight? why it rebuilt all the time?
Theoretically, it should catch all file modifications on the fly and update its database. It shouldn't scan all that much. My copy was doing the same thing until I prevented it from scanning the Windows partition ('cause it kept doing that). Now you can't hear a peep out of it. Spotlight is still very rough around the edges...Any time you add, change, delete files, the index needs to be updated.