Flash as 3.0 Loader Memory extending

Hi, I have a main file with a loader+ 2 buttons in it which loads & unloads 2 external ".swf" files and a trace to monitor the System.totalMemory. PROBLEM IS after  my unload command the memory dosnot get's free and even increasing on every load then unload command.

var loaderObj:Loader
var sp:Sprite= new Sprite()
 
function mcLoad(e:MouseEvent){	
	loaderObj= new Loader();
	loaderObj.name='tension';
 	var str:String="i.jpeg";
	loaderObj.load(new URLRequest(str));
	sp.addChild(loaderObj);
	stage.addChild(sp)
}
 
function mcUnload(e:MouseEvent){
	loaderObj.unload();
	sp.removeChild(loaderObj);
	stage.removeChild(sp)
	trace(System.totalMemory);
}
 
b0.addEventListener(MouseEvent.CLICK,mcLoad);
b1.addEventListener(MouseEvent.CLICK,mcUnload);

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