How long should it take to restore a new iPad from an iCloud backup of an old one?

My original 2010 wi-fi-only 64GB iPad (long since demoted to at-home e-mail/e-reader/web browsing duty) reached the end of its rope. Even though it had 44GB still free, I couldn’t update it beyond iOS 5.1--and many of the apps on there were no longer supported, with the new versions requiring at least iOS 6 or 7. It was also getting extremely unstable and crashing frequently. Way past warranty, and has no trade-in value. I analyzed my needs for an at-home-only iPad (I carry my phones and a new iPad Mini 3 with cellular in my purse) and decided I didn’t need the Air 2’s fingerprint sensor or antiglare screen--but I needed the full-size form factor for my aging eyes. The Air 2 was available in either 16GB (too small, especially considering it runs iOS 8) or 64GB--the latter being way more storage than I’d need. So I backed up the old one to iCloud and bought a new iPad Air, wi-fi-only, 32 GB (just the right amount of storage). Since there was no cell carrier or SIM swap involved, I declined the free in-store personal setup and decided to set it up at home.

About 2-1/2 hrs. ago, I set it up and clicked “restore from” this afternoon’s backup. I downloaded iOS 8.3 (it comes with 8.1), but can’t install it until the restore finishes. The restore seems not to have progressed AT ALL (judging from the grayed-out app icons) over the last hour. How long should roughly 16GB worth of stuff (from a 64GB iPad) take to restore? My phones, and my Minis, restored MUCH faster!