wp-lazy-load free WordPress plugin

This plugin optimizes your page load performance using the jQuery Lazy Load. The img src attributes in your posts are replaced with placeholder tags. The plugin waits for the user to scroll to near the image before it starts loading the image. This improves your page speed as only images that are actually viewed by users are loaded. And your servers will also perform better as they will need to serve fewer images. Credits Thanks to Mika Tuupola for jQuery lazyload