Defrag.NSF+ is a Domino-specific database defragmentation tool that runs as a Domino server task. It intelligently auto-switches between file-level and volume-level defragmentation. Key features include automatic scheduling and tagging of databases for defragmentation, analyzing and reducing database fragmentation, and automated maintenance of system databases. Regular defragmentation with Defrag.NSF+ can significantly speed up backup times and improve database performance.