I’ve gone through your code, I noticed you never use removeChild or delete or anything to remove any particles, running your example I could see the memory usage slowly rising over time. So that’s a bit of a memory leak you might want to patch.

Besides this I also wonder why you keep a particles array which holds all the particles, since Particle extends Sprite, so is allready managed and accesible through getChildAt and addChild etc. (but perhaps an array is faster access, that would be nice to know).