When you have hundreds of images it is best to use James Padolseys scrollstop event. Compate this to page where plugin is disabled or page with larger images.
<script src="jquery.scrollstop.js" type="text/javascript"></script>
<img data-original="img/example.jpg" src="img/grey.gif">
$("img").lazyload({
event: "scrollstop"
});
