PerformanceTests/Parser/query-selector-deep.html - WebKit - Git at Google

 <!DOCTYPE html>
 <html>
 <body>
 <script src="../resources/runner.js"></script>
 <script>
 var parentDiv = document.body;
 for (var i = 0; i < 1000; i++) {
     var div = document.createElement("div");
     div.id = "foo" + i;
     div.className = "bar" + i;
     parentDiv.appendChild(div);
     parentDiv = div;
 }

 var h1 = document.createElement("h1");
 h1.id = "id";
 h1.className = "class";
 parentDiv.appendChild(h1);

 PerfTestRunner.measureRunsPerSecond({
     description: "This benchmark tests querySelector() for an element that appears in the depths in the document",
     run: function() {
         for (var i = 0; i < 100; i++) {
             document.querySelector("h1");
             document.querySelector("#id");
             document.querySelector(".class");
         }
     }});
 </script>
 </body>
 </html>
	<!DOCTYPE html>
	<html>
	<body>
	<script src="../resources/runner.js"></script>
	<script>
	var parentDiv = document.body;
	for (var i = 0; i < 1000; i++) {
	var div = document.createElement("div");
	div.id = "foo" + i;
	div.className = "bar" + i;
	parentDiv.appendChild(div);
	parentDiv = div;
	}

	var h1 = document.createElement("h1");
	h1.id = "id";
	h1.className = "class";
	parentDiv.appendChild(h1);

	PerfTestRunner.measureRunsPerSecond({
	description: "This benchmark tests querySelector() for an element that appears in the depths in the document",
	run: function() {
	for (var i = 0; i < 100; i++) {
	document.querySelector("h1");
	document.querySelector("#id");
	document.querySelector(".class");
	}
	}});
	</script>
	</body>
	</html>