Using the Vector.<T> type and the for each loop is more performant than a conventional array and for loop:
Good:
var list:Vector.<Sprite> = new <Sprite>[];
for each(var sprite:Sprite in list) {
sprite.x += 1;
}
Bad:
var list:Array = [];
for (var i:int = 0; i < list.length; i++) {
var sprite:Sprite = list[i];
sprite.x += 1;
}