Another good article/tutorial from Adobe By Elad Elrom:
Flex data binding pitfalls: common misuses and mistakes
“Data binding—the process of passing the data in one object to another object automatically—is one of the most used and useful features when building Flex and Adobe AIR applications. At the same time, however, data binding can slow application initialization and cause frustration when developers don’t fully understand how the mechanism works. It is a good idea to make sure you are using it correctly and only when needed. In this article, I’ve compiled a list of ten common pitfalls and mistakes that developers are susceptible to when building an application that uses data binding.”
The full article can be read here: http://www.adobe.com/devnet/flex/articles/databinding_pitfalls.html.