As previously noted, several users have reported an issue in which the iPad, iPhone and iPod touch become indefinitely stuck on the backup phase of syncing. Other users report that the backup process is inordinately slow, taking up to 3 hours in some cases. We previously noted a number of fixes for this problem, including disabling the network connection after the sync process has begun, restoring instead of updating, switching USB ports and more.
As an alternative, you can disable the backup process entirely using a tool such as BackOff. This utility allows you to easily toggle the automatic backup function on and off.
Note that you should still occasionally backup your iOS device to protect its data. This utility will, however, allow you to perform routine syncs without the delay of a backup.