Problems with loaded external jpgs

1

i followed the kirupa tutorial on building an external image loader, and modified it to work with back/next buttons to load a range of images. everything works fine, but the problem is after a few cycles through the images, the site starts to lag. i believe the cause is a stack of images that grows as they are loaded. i have been trying to use removeChild and removeChildAt the previous image when the new image is loaded, but cannot get it to work. any help would be greatly appreciated.

var imageLoader:Loader;
var imageNumber:Number=1;
var imageCount:Number=14;

function loadImage(url:String):void {
    // Set properties on my Loader object
    imageLoader = new Loader();
    imageLoader.load(new URLRequest(url));
    imageLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, imageLoaded);
}

loadImage("stills/still"+imageNumber+".jpg");

function imageLoaded(e:Event):void {
    // Load Image
    imageHolder.addChild(imageLoader);
}


function prevImage(evt:MouseEvent):void {
    if (imageNumber==1) {
        imageNumber=imageCount;
        loadImage("stills/still"+imageNumber+".jpg");
    } else {
        imageNumber--;
        loadImage("stills/still"+imageNumber+".jpg");
    }
}

function nextImage(evt:MouseEvent):void {
    if (imageNumber==imageCount) {
        imageNumber=1;
        loadImage("stills/still"+imageNumber+".jpg");
    } else {
        imageNumber++;
        loadImage("stills/still"+imageNumber+".jpg");
    }
}

prev_btn.addEventListener(MouseEvent.CLICK, prevImage);
next_btn.addEventListener(MouseEvent.CLICK, nextImage);