I made a game for Android phones a few years back that would instantiate, at peak, a few thousand agents that would roam around an artificial environment, devou

I made a game for Android phones a few years back that would instantiate, at peak, a few thousand agents that would roam around an artificial environment, devouring renewable resources, before (maybe) reproducing and eventually dying off. So these agent instances were being continually created and destroyed, and the GC lag absolutely killed performance and made the game totally unplayable. It was unplayable even on a Galaxy S2 - a reasonably high-performance phone at the time. Once I implemented object pooling to handle the creation and destruction of these agents, the game ran very smoothly on an S2, and I could even run the smaller simulations on an old HTC Magic I had lying around. It made an enormous difference.