BitmapDataをどうプールするべきか

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

package {
	import flash.display.Graphics;
    import flash.display.Sprite;
	import flash.events.MouseEvent;
	import flash.text.TextField;
	import flash.utils.getTimer;
	import flash.display.BitmapData;
    public class FlashTest extends Sprite {
		private var pooler:BitmapDataPooler;
		
		private var txt:Vector.<TextField>;
		
		private const COUNT:int = 30000;
		
        public function FlashTest() {
            // write as3 code here..
            pooler = new BitmapDataPooler();
			
			txt = new Vector.<TextField>(5);
			
			var i:int = txt.length;
			while (i--)
			{
				txt[i] = new TextField();
				txt[i].autoSize = "left";
				txt[i].y = i * 20;
				addChild(txt[i]);
			}
			
			var btn:Sprite = new Sprite();
			var btn_txt:TextField = new TextField();
			btn_txt.autoSize = "left";
			btn_txt.selectable = false;
			btn_txt.text = "one more test";
			btn_txt.textColor = 0xFFFFFF;
			btn.addChild(btn_txt);
			
			var g:Graphics = btn.graphics;
			
			g.beginFill(0xFF << 24, 1);
			g.drawRect(0, 0, btn.width, btn.height);
			g.endFill();
			
			btn.y = 150;
			addChild(btn);
			
			btn.addEventListener(MouseEvent.CLICK, test);
			
			test(null);
        }
		
		private function test(e:MouseEvent):void 
		{
			var time:int = getTimer();
			var i:int = COUNT;
			var bmd:BitmapData = new BitmapData(10, 10, true, 0x0);
			while (i--)
			{
				pooler.dispose2(bmd);
			}
			
			txt[0].text = String(getTimer() - time) + " msec : プールに貯めるのにかかった時間";
			time = getTimer();
			
			i = COUNT;
			while (i--)
			{
				bmd = pooler.getNamamono();
			}
			
			txt[1].text = String(getTimer() - time) + " msec :　プールからfillRectで透明にしてから取り出すのにかかった時間";
			
			i = COUNT;
			var vec:Vector.<BitmapData> = new Vector.<BitmapData>(i);
			while (i--)
			{
				vec[i] = new BitmapData(10, 10, true, 0x0);
			}
			
			time = getTimer();
			
			i = COUNT;
			while (i--)
			{
				pooler.dispose1(vec.pop());
			}
			
			txt[2].text = String(getTimer() - time) + " msec : プールに貯めたように見せかけるのにかかった時間";
			
			time = getTimer();
			
			i = COUNT;
			while (i--)
			{
				bmd = pooler.getClone();
			}
			
			txt[3].text = String(getTimer() - time) + " msec : プールから取り出したかのようにclone()するのにかかった時間";
			
			i = COUNT;
			while (i--)
			{
				bmd = new BitmapData(10, 10, true, 0x0);
			}
			
			txt[4].text = String(getTimer() - time) + " msec : 普通にnewするのにかかった時間";
			
		}
    }
}

import flash.display.BitmapData
class BitmapDataPooler
{
	private var pool:Vector.<BitmapData>;
	
	public function getClone():BitmapData
	{
		var bmd:BitmapData = pool[0];
		return bmd.clone();
	}
	
	public function getNamamono():BitmapData
	{
		var bmd:BitmapData = pool.pop();
		bmd.fillRect(bmd.rect, 0x0);
		return bmd;
	}
	
	public function dispose1(bmd:BitmapData):void
	{
		if (pool.length)
		{
			//bmd.dispose();
		}
		else
		{
			bmd.fillRect(bmd.rect, 0x0);
			pool.push(bmd);
		}
	}
	
	public function dispose2(bmd:BitmapData):void
	{
		pool.push(bmd);
	}
	
	public function BitmapDataPooler()
	{
		pool = new Vector.<BitmapData>();
	}
}