Macbook Air + External Display Unresponsive while charging

I have an early 2011 11" Macbook Air 2GB RAM 64GB SSD Lion 10.7.3. When I hook up the Air to my LED TV to use as a display (via Displayport and VGA), the Macbook Air works fine either in the mirroring mode. However the moment I plug in the charger, the Air slows to a crawl. The keyboard and trackpad slow down tremendously in terms of responsiveness. This happens in either mirror or clamshell mode. I would love to use this while hooked up to a bigger display, but it seems that this would only be possible without charging it. Any help?