title: KVO rocks. Now how do I use it asynchronously?
body: <p>I am sold on KVO but if used in the obvious way it is synchronous. I would like to use it in a situation where I am firing off many KVO messages in rapid succession and it is causing my app to grind to a halt as the KVO messages are handled. Can someone suggest an approach - perhaps using <code>NSOperation</code> or <code>NSThread</code> - that will work here?</p>
  
  <p>My goal is to retain the decoupled, flexibility of KVO if possible.</p>