Adobe AIR memory leak loading SWFs

I was plagued by a memory leak that would crash my application after a few hours. The application had worked fine in the past but now was having issues and I thought it might have to do with using newer SDK's.

In the end I discovered that if I loaded external swf that had been compiled in debug mode, they would not clear completely on unload and cause a memory leak.

Compiling in release mode fixed the issue. Spent 3 days trying to figure it out.