Florian Brinkmann

Lazy loading plugin that supports images, iFrames, video and audio elements and uses the lightweight lazysizes script. With manual modification of the markup it is also possible to lazy load background images, scripts, and styles.
Lazy loads (without the need of any manually modifications):
<ul>
<li>Images inserted via <code>img</code> or <code>picture</code> in posts, pages, Custom Post Types, Text Widgets, …</li>
<li>Post thumbnails.</li>
<li>Inline background images.</li>
<li>Or all images and other enabled media in the markup (that is not excluded or already has a lazy loading attribute), via the option to process the complete markup.</li>
<li>iFrames.*</li>
<li>Video elements.*</li>
<li>Audio elements.*</li>
</ul>
* Can be enabled in the plugin options.
The plugin comes with the following options (under Settings › Media › Lazy Loader options):
<ul>
<li>Do not lazy load elements with specific CSS classes (you can use the class <code>skip-lazy</code> by default).</li>
<li>Add filters that should be processed by Lazy Loader.</li>
<li>Enable lazy loading for iFrames.</li>
<li>Include the <a href="https://github.com/aFarkas/lazysizes/tree/gh-pages/plugins/native-loading" rel="nofollow ugc">lazysizes native loading plugin</a> that modifies images and iFrames to use the native lazy loading feature of browsers that already support it.</li>
<li>Include the <a href="https://github.com/aFarkas/lazysizes/tree/gh-pages/plugins/unveilhooks" rel="nofollow ugc">lazysizes unveilhooks plugin</a> that adds support for more elements, for example, video and audio elements.*</li>
<li>Enable lazy loading for the poster frame of video elements.</li>
<li>Enable lazy loading for audio elements.</li>
<li>Enable lazy loading for inline background images.</li>
<li>Display a loading spinner.</li>
<li>Disable the plugin on specific posts/pages (this shows a checkbox in the edit view of all public post types (except attachments) to disable lazy loading for an entire post).</li>
<li>Process the complete markup of the site.</li>
<li>A textarea to modify the default lazysizes config values.</li>
</ul>
* The unveilhooks extension of lazysizes supports more than video and audio elements, but you need to manually modify the markup to use it for:
<ul>
<li>Background images not inserted with inline styles.</li>
<li>Scripts.</li>
<li>Styles.</li>
</ul>
The plugin adds a <code>noscript</code> element as fallback for disabled JavaScript (can be disabled with the <code>lazy_loader_generate_noscript</code> filter).
You can disable lazy loading for elements with specific CSS classes by defining them via the plugin settings (Settings › Media › Lazy Loader options). Or use the <code>skip-lazy</code> class or the <code>data-skip-lazy</code> attribute. <code>skip-lazy</code> and <code>data-skip-lazy</code> also work on wrapper elements to exclude the wrapper and its children from being processed.

Lazy Loader

Absolutely the best plugin for lazy loading, I use it for years.

Great plugin

This is an incredible plugin, it works great on one of my websites but unfortunately, it doesn't work at all on my other staging website, don't know if I am doing something wrong.

Works on some themes

Lazy loading plugin that supports images, iFrames, video and audio elements and uses the lightweight lazysizes script. With manual modification of the …

Patrick Sletvold

lazysizes is a WordPress plugin for the high performance, SEO-friendly and auto-triggering lazyloader <a href="https://github.com/aFarkas/lazysizes" rel="nofollow ugc">with the same name</a>. Support includes images (including responsive images with <code>srcset</code> and the <code>picture</code> tag), iframes, scripts/widgets and much more. It also prioritizes resources by differentiating between crucial in view and near view elements to make perceived performance even faster. Additionally, you can add low-res/blurry placeholder images using the Blurhash algorithm.
This plugin works by loading the lazysizes script and replacing the <code>src</code> and <code>srcset</code> attributes with <code>data-src</code> and <code>data-srcset</code> on the front end of a WordPress site. When a post or page is loaded, the lazysizes javascript will load the images, iframes etc. dynamically when needed. All you need to do is to enable the plugin, and possibly tweak a few settings to your liking.
Thanks to aFarkas and contributors for making the <a href="https://github.com/aFarkas/lazysizes" rel="nofollow ugc">lazysizes library</a> possible, and for letting me use the same name.
Also thanks to dbhynds who made the Lazy Load XT plugin, which this plugin is based on.

lazysizes

High performance and SEO friendly lazy loader for images, iframes and more. Many features, like low-res Blurhash placeholders and image fade-in

Lazy Loader vs lazysizes