I'm doing an application that puts tons of sprites on the screen in random position, like throwing cards on a table, but after a while it starts to drop the fps, because all the sprites still there. What I would like to do is adding the sprites but like an image, what's behind isn't stored. There are some way to do that?

the code looks like this:

var mySprite:MySprite = new MySprite();
mySprite.x = random;
mySprite.y = random;
mySprite.rotation = random;
addChild(mySprite);

Ps: I will not have to mess with them after they are on the screen.