Spotlight's Impact on PowerBook Battery Life?

Viltvodlian Deoderan asks: "So, Spotlight for Mac OS X Tiger is very cool. I can now let my innate ability to disorganize things shine through. However, when using my PowerBook unplugged, it seems that my battery lasts a noticeably less time. A close reading of Ars Technica's description of how spotlight works suggests that this is due to keeping the index file up-to-date on disk. Has anyone else noticed the same thing? Does someone have a better explanation for why my battery seems to drain out, prematurely? Is there some way real-time indexing can be turned off to conserve power?"