20,000 particles are moving by each tweening engines. BetweenAS3 Alpha r3022 (FlashPlayer10 ver.) BetweenAS3 Alpha r3022 (FlashPlayer9 ver.) Tweensy 0.2.2 TweenMax 10.11 Tweener 1.33.74 (4,000 particles because it can't process 20,000 particles) GTween Beta5 All Source (ZIP) BetweenAS3, fast, powerful and professional new tweening engine.