While tracking down the source of a memory leak, I stumbled upon a strange issue with AS 3.0 and loading external flash movies. From what I can tell this somehow related to the custom classes stored inside the loaded movie. I have two versions of a basic file that contains one image on the stage (I also tried this with vector graphics with the same effect). One version has a custom document class (just a simple extends MovieClip with no additional code) and the other has no document class.
The graph below depicts the memory usage from loading the file without a document class. It performs the garbage collection as you would expect after each unload operation.
However when I try to load and unload the same file with a document class, I get the following memory usage graph. As you can see, memory usage is slowly creeping up with each load operation.
It almost seems that Flash is caching the class files, so I tried changing the application domain for the loaded content without success. Even if Flash was caching the class files I would assume that it would be able to detect that it had already cached the document class and simply re-load the cached version. Any ideas on what is going on here?
