WordPress.org

Felix Arntz

Andrew Ozz

Lazy Loading Feature Plugin is an official plugin maintained by the WordPress team. It is intended for testing of automatically adding the <code>loading</code> HTML attribute to images and other elements that support it.
More information about the <code>loading</code> attribute: 
Description: <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#attr-loading" rel="nofollow ugc">https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#attr-loading</a>. 
HTML Specification: <a href="https://html.spec.whatwg.org/multipage/embedded-content.html#attr-img-loading" rel="nofollow ugc">https://html.spec.whatwg.org/multipage/embedded-content.html#attr-img-loading</a>.
Currently the <code>loading</code> attribute is supported in the following browsers: <a href="https://caniuse.com/#feat=loading-lazy-attr" rel="nofollow ugc">https://caniuse.com/#feat=loading-lazy-attr</a>.
To test, install and enable the plugin. It will automatically add <code>loading="lazy"</code> attributes to all images in all new and existing posts, pages, and text widgets on the front-end.
Then use one of the browsers that support it (Chrome, Opera, Firefox, Edge, Android, etc.) and visit the site. Best would be to test over a slower connection, with a phone, etc. and test web pages that have a lot of images, like gallery posts.
<h4>Things to look for</h4>
<ul>
<li>Obvious bugs, for example images are missing.</li>
<li>Try to scroll down as soon as the page loads. All images should be at their places, and the page shouldn’t “jump” when images are loaded.</li>
</ul>
<h4>Note to developers</h4>
This plugin is intended for testing. If the tests are successful, this functionality will be added to WordPress, but the exact code may change, perhaps significantly.
When testing, please also test the filters added by this plugin, and provide feedback at <a href="https://github.com/WordPress/wp-lazy-loading" rel="nofollow ugc">https://github.com/WordPress/wp-lazy-loading</a> or at <a href="https://core.trac.wordpress.org/ticket/44427" rel="nofollow ugc">https://core.trac.wordpress.org/ticket/44427</a>.

Lazy Loading Feature Plugin

WordPress feature plugin for testing and experimenting with automatically adding the "loading" HTML attribute. Not for production use.

Delicious Brains

Brad Touesnard

Image Processing Queue is an alternative to on-the-fly (OTF) image processing (e.g. <a href="https://github.com/syamilmj/Aqua-Resizer" rel="nofollow ugc">Aqua Resizer</a>) 
for WordPress themes.
Like OTF image processing, it allows theme developers to define image sizes for specific theme 
contexts rather than defining a size for all uploaded images. This greatly reduces the number of 
resized images and hence reduces disk space usage and the wait time when uploading an image.
Image Processing Queue differs from OTF image processing in how it behaves when an image doesn’t 
exist yet. OTF generates the image right away and the end-user has to wait for the image to be 
generated. With Image Processing Queue there’s no waiting. It immediately returns an image that 
already exists (that is the closest fit to the image size requested) and adds the image size to 
a queue. Image sizes are quietly generated in the background using <a href="https://github.com/A5hleyRich/wp-queue" rel="nofollow ugc">WP Queue</a>.
Image Processing Queue also accommodates responsive themes much better than OTF. It allows theme 
developers to define a list of image sizes that will work best for their theme’s responsive 
breakpoints. Images generated by Image Processing Queue are added to the post meta so that WordPress 
core’s responsive functions will automatically add them to the <code>srcset</code> and delete them from the 
filesystem when the image is deleted from the Media Library.

Image Processing Queue

It works!

tbh, it took me a few minutes to fully understand how this library would benefit my workflow and my clients - but once I started to grasp the changes in development and how I wouldn't be running Regenerate Thumbnails every time I needed a new image size, it clicked!

I think with some more detailed documentation and usage examples this could be a near perfect solution to the image size problem in many themes and plugins.



This could be a game changer!

Real intresting approach and something that should be considered for WP Core - especially the Batch Processing Stuff isn#t only useful for images ...

Lazy Loading Feature Plugin vs Image Processing Queue