Ghost 12 backup times have gotten incredibly long

Just recently I've noticed that my Ghost 12 incremental backups have gotten outrageously long.  Today's backup--size 512.0 kb--had an elapsed time of 5 hrs, 27 mins, 37 sec!!  This never used to be like this.  I did a manual incremental on the same drive yesterday--size 1.0 mb--and it took 33 seconds.

 

Something is wrong but I'm unclear how to tell what.  I back up across my network to NAS devices.  My only guess is some kind of issue with network thruput.  Does anyone have any ideas how to monitor what's going on, see why Ghost is taking so long to determine that almost no change has taken place on a drive?