Apple has released MacBook Air EFI Firmware Update 2.1, aimed at addressing various issues with mid-2011 MacBook Airs.
The firmware update improves Lion Recovery over an Internet connection, and also resolves issues with Apple Thunderbolt Display and Thunderbolt Target Disk Mode performance on affected Airs.
You must plug in your MacBook Air before installing the firmware update. You’ll see a grey screen with a progress bar during the firmware’s installation, and Apple warns that you shouldn’t disturb or shut off your MacBook Air while the updater is running.
The firmware update requires Mac OS X Lion 10.7 or later.