ActionScript 3.0 :: Flash - FrameRate Drop With MovieClips?

I'm currently trying to make a little game but I experience now some loss of framerate while adding "bullets" in the gameI'll not enter in the full code source as it will take some time but basicallyI got a mainGame class, a Player class, and a bulletClassthe mainGame class contain the game loop working like this, main timer cecks:-loop function of the Player class, checking if space is pressed,if it's pressed a bullet is displayed with this line in the player class:Code://main_class is the MainGame class and the container is the main displaymain_class.container.addChild(new Bullet(x, y, otation,main_class));//then the bullet add itself in a _bulletArray of the Main Gam class-loop function of the bullet Class, for each bullet cointained in the _bulletArray,it moves the bullet from some X, and if it's out of view of the screen it destroying itself from the array and with a removeChild of the display list like this:

Code:
y += vy;
x += vx;

[code].....