un solo consiglio potresti ridurre un po di AS

codice:
function loadImage(_index){
	if(_index != undefined && _index != ""){
	   this.preloader.bar._xscale = 0;
	   this.preloader.info.text = "";
	   this.imagermenu.loadMovie("immagini_design/d" + _index + ".swf");
           this.preloader._visible = 1;
	   this.loading = true;
	   this.onEnterFrame = function(){
		var car = this.imagermenu.getBytesLoaded();
		var tot = this.imagermenu.getBytesTotal();
                this.preloader.bar._xscale = Math.round(car/tot*100);
		this.preloader.info.text = "Loading menu " + this._index + " - " + perc + "%";
                if(car == tot && car >1024){
                   // caricato immagine ok
                   this.preloader._visible = 0;
		   this.initialized = true;
		   this.loading = false;
		   delete this.onEnterFrame;
		   this.gotoAndPlay("in");
		}
	   }
     }
}