Reduce CPU load in game

Question

Hello everyone,
Having a problem with a game, The cpu load at the start when all the elements are on the stage is between 120 - 150%. Far too high. I reduced the frame rate from 30 to 24 and now the cpu load is around 100 - 125% which is still too high for my liking !! I'm wondering if this code can be optimized, I'm sure this is the cause, it's running within a movieclip class on 15 movies at the start.. can anyone help ?? Thanks in advance :-
       private function onEnterFrameHandler (event:Event) : void {
            this.vy += gravity;
            this.x += vx;
            this.y += vy;
            var left:Number = 0;
            var right:Number = stage.stageWidth;
            var top:Number = 0;
            var bottom:Number = stage.stageHeight;
            if(this.x + this.width > right)
                this.x = right - this.width;
                vx *= bounce;
            else if(this.x - this.width < left)
                this.x = left + this.width;
                vx *= bounce;
            if(this.y + this.height > bottom)
                this.y = bottom - this.height;
                vy *= bounce;
            else if(this.y - this.height < top)
                this.y = top + this.height;
                vy *= bounce;

Answer 1

First, you can drop all those this' - there's no need for them. I never use this in as3 anymore.
Second - get rid of all your local vars. Is stage.stageWidth changing? Probably not... so don't poll the player for it on each frame. Same with the clip extents.
Something more like so:
private var left:int = 0;
private var right:int = stage.stageWidth;
private var top:int = 0;
private var bottom:int = stage.stageHeight;
private var clipWidth:int = width;
private var clipHeight:int = height;
private function onEnterFrameHandler (event:Event) : void
    vy += gravity;
    x += vx;
    y += vy;         
    if(x + clipWidth > right)
        x = right - clipWidth;
        vx *= bounce;
    else if(x - clipWidth < left)
        x = left + clipWidth;
        vx *= bounce;
    if(y + clipHeight > bottom)
        y = bottom - clipHeight;
        vy *= bounce;
    else if(y - clipHeight < top)
        y = top + clipHeight;
        vy *= bounce;