How long does it take make an encrypted back up of an iPhone 6

In the past, when backing up my wife's iPhone 6 64G, the sync process has taken less than half an hour.

This time, I decided to do the right thing and finally start making encrypted back ups of the phone. That was almost 4 hours ago. Is this normal?

Seems like I'm hung on "(step 5 of 5) waiting for changes to be applied."

Progress bar indicator suggests it is done. But I know you can't trust progress bars.

No idea if it's actually doing anything... I know encryption will slow things...

Activity monitor doesn't show iTunes pegging the cpu or anything, only 10% occasionally jumping to 15.

The phone is 64G, but only 18 is used. Does it encrypt the whole thing? (Seems I remember something about that somewhere.)

I'm THIS close to just aborting, but, you know I've got that "sunk cost" thing nagging the back of my mind.

Thanks