OneNote runs several features in the background such as text and hadwriting recognition, search indexing, and synchronization. If you are running this application on a battery powered computer (laptop, Tablet PC), you can improve life of the battery by changing the battery options in OneNote as instructed by this tech-recipe:
1. Open OneNote.
2. Click Tools and select Options.
3. In the Category pane, select Other.
4. Under Battery Options, select the appropriate setting from the Optimize for the following battery life dropdown.