A quick browse of Apple - Support - Discussions - Syncing makes it clear that it is a general problem and not an isolated one.
So from all I have read thus far it looks as if Zenio is the number one offender. ESPN app could also be an issue. The sync cable that is used ness to be the original from Apple for the iPad, not generic. The anti virus application may need to be disabled during the backup. It would seem that once you have completed your backup , you may just want to disable the option to perform a backup each time you connect your iPad. Instead just perform a sync of your apps and music or what have you.
Here is one thing it took me for ever to figure out....My Back ups were taking foooor evvverrr and I mean for ever, eventually I figured out (and that took a looong time) that my old Wacom tablet was to culprit. Took it off my system and backups take less than a minute (from taking hours and hours while it was hooked up).
I guess my over all point here is your BU's are taking a long time start to remove some of the peripherals you have hooked up via USB, that may just be the answer. Even if you have to remove something temporarily just to do the BU and then hook it back up it may be the difference between pulling your hair out and getting the job done.
Well thanis for this as it never occurred to me. I have a Wacom and other peripherals via USB. i'll try this next backup.