A memory issue is probably happening during runtime, creating or saving things that aren't getting cleaned up automatically. Your initial data structures are probably fine, and there aren't THAT many moths being created through the course of the game. Is it possible that the clicking particle effect or something to do with adding store currency is creating objects that aren't destroyed? Those are the only things I can think of that happen at a big enough of a scale to cause an issue. Or maybe something meant to manage the creation of hybrid moths?