iPad Air 2 screen slow/unresponsive when plugged in.

Just got an iPad Air 2 128 GB yesterday. It is up to date with iOS 8.1.2.

I noticed right away last night that it was having trouble keeping up with me while I was typing a text message to a friend. Letters would skip, or sometimes they would double or triple.

I seem to have narrowed it down to only happening when the iPad is plugged in.

I've tried the following combinations:

- Lightning cable that came with the new iPad, plugged in to my MacBook Pro = delays

- Lightning cable that I use for my iPhone 5, plugged in to my MacBook Pro = delays

- New Lightning cable plugged in to the new plug block = delays

- Old Lightning cable plugged in to the new plug block = delays

So I don't believe it's the cable, or being plugged into the laptop rather than the wall. As soon as the cable is unplugged, the iPad is fine. When plugged in, I can test by bringing up the keyboard and typing AQAQAQAQAQAQ for instance, and you can see the keyboard not registering several of my touches. Unplug, do the same test, it's 100% responsive. I have reset the iPad (it was brand new to begin with anyway), that didn't help. I left it plugged in to iTunes overnight (thinking maybe it's because it was brand new and catching up to all my apps), but today, it's exactly the same.

I really don't want to have to go back to the maul on Christmas week... so I'm hoping there's something else going on.

Anyone?