Vertical Scrolling Movie clip

[the_first_noel]

i sort of sourced online and created a code that i thought would be suitable for vertical scrolling for a touch screen app am currently building with AS3.
it works fairly well, just that when i test it on the touch screen it isn't so fluid and responsive to my touch.
its a movie clip (scroll_mc) that has been masked and rests in a border movie clip (stageborder)

here's the code:

var speed:Number;
var speedArray:Array;
var prevY:Number;

var DRAG:Number = 20;

var HEIGHT:int = 360;

scroll_mc.addEventListener(MouseEvent.MOUSE_DOWN, onDown);

function onDown(evt:MouseEvent):void {
	speedArray = new Array(0,0,0,0,0,0,0,0,0,0);
	speed = 0;
	prevY = this.mouseY;
	stageborder.addEventListener(Event.ENTER_FRAME, onDownEnter);
	stageborder.addEventListener(MouseEvent.MOUSE_UP, onUp);
}

function onDownEnter(evt:Event):void {
	var sp = this.mouseY - prevY;
	scroll_mc.y += sp;
	if (scroll_mc.y < (HEIGHT-scroll_mc.height)) {
		scroll_mc.y = (HEIGHT-scroll_mc.height);
	}
	else if (scroll_mc.y > stageborder.y) {
		scroll_mc.y = stageborder.y;
	}
	speedArray.push(sp);
	speedArray.shift();
	prevY = this.mouseY;
}

function onUp(evt:MouseEvent):void {
	stageborder.removeEventListener(Event.ENTER_FRAME, onDownEnter);
	stageborder.removeEventListener(MouseEvent.MOUSE_UP, onUp);
	
	speed = 0;
	for (var i:int = 0; i<speedArray.length; i++) {
		speed += speedArray[i];
	}
	speed /= speedArray.length;
	
	addEventListener(Event.ENTER_FRAME, onEnter);
}

function onEnter(evt:Event):void {
	if (Math.abs(speed) < .5) {
		speed = 0;
	}
	if (speed < 0) {
		if (scroll_mc.y > (HEIGHT-scroll_mc.height) - speed) {
			scroll_mc.y += speed;
			speed -= speed/DRAG;
		}
		else {
			scroll_mc.y = (HEIGHT-scroll_mc.height);
			speed = 0;
		}
	}
	else {
		if (scroll_mc.y < 0-speed) {
			scroll_mc.y += speed;
			speed -= speed/DRAG;
		}
		else {
			scroll_mc.y = 0;
			speed = 0;
		}
	}
}

i have also attached the demo file am working on,
can anybody help me in tweaking it so the scrolling is more fluid?


thanks in advance

williams