Sadly you had to know the underlying structure of the components to work around the performance issues. Main pain point I had to work around was the fact that most containers where scrollable by default and brought a huge update cost. For a time my job was to convert components written by a visual developer in mxml into custom components written in AS3. I knew the runtime model pretty well and was able to layout complex components in code. These had the benefits of not being nested into multiple UIComponent containers/component layers which all hooked into the UI update loop. Ah good times :)