Justin Downey

This plugin adds the <code>loading</code> attribute to IMG tags found when filtering <code>the_content()</code> to support native image lazy loading.
For more information about lazy loading images using this new native browser image attribute, check out this article: <a href="https://addyosmani.com/blog/lazy-loading/" rel="nofollow ugc">https://addyosmani.com/blog/lazy-loading/</a> and for a little more depth into what we’re doing here, check out our <a href="https://jdmdig.it/30nXp7h" rel="nofollow ugc">explainer post</a>.
Historically, to limit the impact offscreen images have on page load times, developers have needed to use a JavaScript library (like <a href="https://github.com/aFarkas/lazysizes" rel="nofollow ugc">LazySizes</a> or <a href="https://www.andreaverlicchi.eu/lazyload/" rel="nofollow ugc">Vanilla-LazyLoad</a>) in order to defer fetching these images until a user scrolls near them. What if the browser could avoid loading these offscreen images for you?
The <code>loading</code> attribute instructs a browser to defer loading offscreen images until users scroll near them. It comes in three flavors: eager, auto, and lazy. Install this plugin and you can set the first image’s loading attribute and the loading attribute for all the subsequent images sent through <code>the_content()</code> in the plugin’s settings page.
Simple is Beautiful
There is no JavaScript or CSS included in the plugin. It just works in browsers that support the new <code>loading</code> image attribute.
For browsers that don’t support this new image loading attribute, that’s ok. You can still use whatever JavaScript-based image lazy loader you want as a fallback until browser support becomes a little more mainstream.

Native Image Lazy Loading

Automatically add the new loading attribute to images within your content to support native image lazy loading.

Processby

Lazy loading images and iframes to speed up sites page load speed. Compatible with WooCommerce. 
This plugin uses <a href="https://github.com/aFarkas/lazysizes" rel="nofollow ugc">lazysizes</a> – is the most popular, high performance and SEO friendly lazy loader for images. 
<a href="https://processby.com/lazy-load-wordpress/#gallery-demo" rel="nofollow ugc">Plugin demo</a>
<h4>Features</h4>
<ul>
<li>Lazy loading images inserted in posts, pages, custom post types, text widgets;</li>
<li>Lazy loading image gallery, image widget, image gallery widget;</li>
<li>Lazy loading product images, product category images in WooCommerce;</li>
<li>Lazy loading iframes;</li>
<li>Improves <a href="https://developers.google.com/speed/pagespeed/insights/" rel="nofollow ugc">PageSpeed Insights</a> Results, fixes error “defer offscreen images”;</li>
<li>Lightweight and fast.</li>
</ul>

Lazy Load Optimizer

I have tried many Lazy Loading and even WP Rocket own Lazy Loading but this one works perfectly fine and my score in Google Site Speed Improved a lot! Thanks guys!

Best Lazy Loading

This plug-in will transform all your actual PNG media to WebP + automatically transform them in WebP when downloading new loud formats, in a beautiful manner. Simple in the presentation but powerful in the application. I recommend it a lot !

Great Plugin for saving time

Lazy loading images and iframes to speed up sites page load speed.

Native Image Lazy Loading vs Lazy Load Optimizer