I’ve just found an article on InsideRIA that is actually a list of techniques and best practices for optimizing ActionScript 3.0 code and Flex applications. This is a must know for AS3 / Flex developers. The article has a list of references – information on which the article was based. I really recommend you reading through those articles and also through the comments to the article. You’ll find there a few more links to optimization articles and some extra notes on the information in the article.

Update: Grant Skinner has also published an AS3 performance tester. You might want to check it out. Oh, and I had another post about an interesting AS3 performance tester application. There’s a wiki page too, created by Joa Ebert, listing some AS3 optimization tips.