Over time, the database file on hard drive can fragment. This can degrade server performance, especially with large designs. By default, the iCDB Server automatically defragments the database when you shut it down, but if you begin to have performance issues, you can defragment the database manually.
You can specify which users can run defragmentation by setting the DefragmentDatabase permissions as described in Setting Permissions for Server Manager Tasks.
You can toggle whether or not the iCDB Server defragments the database on shutdown with the DBDefragmentOnShutdownconfiguration file parameter.