<body>
<script>var tstart = new Date();
var string = '';
for (var i = 0; i < 600; i++) {
string += '<a href="javascript.ru">JavaScript.Ru</a><br>';
}
document.body.innerHTML += string;
alert(new Date() - tstart + 'ms');
</script>
</body>
<body>
<script>var tstart = new Date();
var links, link;
links = document.createDocumentFragment();
for (var i = 0; i < 600; i++) {
link = document.createElement('a');
link.href = 'javascript.ru';
link.textContent = 'JavaScript.Ru';
links.appendChild(link);
links.appendChild(document.createElement('br'));
}
document.body.appendChild(links);
alert(new Date() - tstart + 'ms');
</script>
</body>