I have been having issues finding drive enclosures that are compatible with Apple’s new USB 3.0 ports. Some have issues that make them unusable, and others work okay but don’t perform at the speeds they should be. However, I have found one enclosure that works great with my new MacBook Air: the Vantec NexStar3.
This enclosure is easy to install, has no issues with my MacBook Air, is quiet, and most importantly, it is fast. Here is a performance chart of the MacBook Air’s internal drive, the Vantec, and a USB 2.0 enclosure: