Comparing loop speed with incrementing and decrementing a variable

/**
 * Copyright Fumio ( http://wonderfl.net/user/Fumio )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/zWDY
 */

package {
	import flash.display.Sprite;
	import flash.utils.getTimer;
	import flash.text.TextField;
	import flash.text.TextFieldAutoSize;
	import flash.text.TextFormat;
	import flash.text.TextFormatAlign;
	[SWF(width = "240",height = "180")]
	public class Loop_of_increment_vs_decrement extends Sprite {
		private const AMOUNT:uint = 100000000;
		private var my_txt:TextField = new TextField();
		private var label_txt:TextField = new TextField();
		private var my_fmt:TextFormat = new TextFormat();
		public function Loop_of_increment_vs_decrement() {
			// Creating a TextField for display
			createTextField();
			// Starting Test
			decrement();
			increment();
		}
		private function decrement():void {
			var nAmount:int = AMOUNT - 1;
			// var nEnd:int = 0;
			var started:int = getTimer();
			for (var i:int = nAmount; i >= 0; i--) {
			// for (var i:int = nAmount; i >= nEnd; i--) {
				var temp:int = i;
			}
			xTrace("decrement", getTimer() - started);
		}
		private function increment():void {
			var nAmount:uint = AMOUNT;
			var started:int = getTimer();
			for (var i:uint = 0; i < nAmount; i++) {
				var temp:uint = i;
			}
			xTrace("increment", getTimer() - started);
		}
		private function createTextField():void {
			addChild(my_txt);
			addChild(label_txt);
			my_fmt.align = TextFormatAlign.RIGHT;
			my_txt.x +=  50;
			my_txt.defaultTextFormat = my_fmt;
			my_txt.autoSize = TextFieldAutoSize.RIGHT;
			label_txt.autoSize = TextFieldAutoSize.LEFT;
		}
		private function xTrace(_str:String,n:int):void {
			my_txt.appendText((String(n) + "\n"));
			label_txt.appendText(((_str + ":") + "\n"));
		}
	}
}