Stress

// *** CORE ***
function stress(f){var n=arguments[1]||100,i,t,s=new Date();for(i=0;i<n;++i)f();t=((new Date())-s);return{handler:f,total:t,each:t/n};}
 
 
// *** EXAMPLE ***
// return total time of 100 enforcements function
alert(stress(function(){
	var tags = document.getElementsByTagName("*");
	for(var i = 0; i < tags.lenght; ++i){
		tags[i].innerHTML = i;
	}
}).total);