I give the drawer.* a quick look. The process seems to be heavy.
In the Citrus Engine we use emibap tool for quick prototyping. It shouldn't be used in a final product, you should make TextureAtlas instead.
From what I understand of drawer.* library, it converts your flash symbol into Starling MC. Even if it's asynchronous, it requests some computation time whereas we could only focus on loading texture atlas needed.
This tool provide great options, but I'm not sure that from a performance/memory point of view it is better than loading external xml/png. Maybe I'm missing something?