Flex Performance Presentation by David George
There is a create Presentation on “Flex Performance & Tips” by David George at the link below.
http://adobedev.adobe.acrobat.com/p71169528/
The main areas of performance consideration for your Flex applications are Object creation, Measurement/layout and Rendering. I found the object creation section to be the most helpful for my past experience but the whole presentation is worth viewing and reviewing for any heavy Flex developer.