Sometime ago I tried making a game compatible with flash and iOS with Stencyl(free), I have faced memory leaks leading to frame-rate drops.
The objective was to make an endless game, with procedural level generation. It used a lot of 'create recycled' and 'recycle self' for multiple actor kinds. As the game progressed, the frame-rate remained nice 60 for the first 10 seconds, then started dropping and in the next 10 seconds ultimately to 4-5 fps... The results were somehow almost the same in case of recycling old actors and, simply creating & killing actors (not recycling at all)...
I spent quite some time with it, and the only possibility remaining is memory leaks... The game is closed now, i can send stencyl the source file if the need it for some kind of engine debug purpose