wp-lazy-load

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

1. Click Plugins > Add New in the WordPress admin panel.
2. Search for “wp-lazy-load” and install.

Customization

The threshold parameter controls the distance in pixels that the your
viewers need to be close to to trigger loading of images. Default is 200
pixels.

The plugin uses a transparent gif as the placeholder image by default.
This can be changed by adding a custom placeholder image to your current
themes wp-lazy-load subdirectory.

For eg:- if you add red.gif to {current_theme}/wp-lazy-load/red.gif
and then change the plugin settings to use red.gif.

Then the placeholder for your images will use this red.gif image
instead.

• Can I change the placeholder image?

Yes, see the customization section under Installation.