Originally Posted by
phreddyl Are you using it with the charger and brick that came with it? If you use the iPhone brick it's very slow.
I think he's talking about it's operation more than it's charging speed. OP, of course, please let me know if I'm wrong.
I don't yet own an Air 2 either but from what I understand while it's charging it is listening for the Hey Siri hotword, so it's possible that this 'subroutine' has gone astray? That's about the only thing I can think of.
Have you attempted to reinstall the OS on the device? If you have, was the result the same? Could save you a Genius Bar trip.