What USB cable are you using? I can recreate this problem if I turn down the usb speed to minimum and use a very poor usb cable.
Also check if the Asiair is receiving enough power.
Remember, that the Asiair needs to send 5V through the usb cables, beside the 12 volt plugs.
That's why the big Amp requirement on the power adapters. Needs to be 12 volts and 3-5 amps. 5amp is the safe bet.
Poor electric power to the unit will cause all sorts of issues, including slow usb, slow/disconnecting wifi/ corrupted images and even poor guiding if it can't send the pulses right to the mount.