Recently I saw a screencast from Deepa Subramaniam at Max2008 on how to create new components in Flex 3 (link). I would urge everybody to watch this video if you're not familiar with this topic.

Something I noticed in this video was the use of Bindable metadata tag with event name specified. If you make a setter Bindable, then it's kinda of a performance loss to trigger the binding if the new value that's being set is the same as the old value. Here's a way to improve this:

PLAIN TEXT
Actionscript:
  1. [Bindable(event="xChanged")]
  2. public function get x():Number{ return _x; }
  3. public function set x(value:Number):void{
  4. if(_x != value){
  5. ...
  6. dispatchEvent(new Event("xChanged"));
  7. }
  8. }