Upload or extract the lazy-widget-loader folder to your site’s /wp-content/plugins/ directory. Or you could use the Add new option found in the Plugins menu in WordPress.
Enable the plugin from the Plugins menu in WordPress.
You’re ready to go. To enable lazy loading for any widget, go to your Widgets section under the Appearance menu and check Lazy Loading on every widget that should be loaded after the main page’s content is ready.
Hey! Now would be a good time to look at the Itthinx LazyLoader, it adds some really cool features like on demand asynchronous loading for content and widgets. Also, both plugins really work together and the additional features that Itthinx LazyLoader provides are available along with Lazy Widget Loader’s standard options on every widget.