WordPress Lazy Loading Implementation Guide

In this implementation guide for page loading, performance & speed, we'll show you how to easily lazy load images & videos in WordPress

Updated on February 13, 2024
WordPress Lazy Loading Implementation Guide

Would you like to use lazy loading for images in WordPress? Lazy load allows your website to load images only when a user scrolls down to the specific image. You can see it in action on many popular websites like Buzzfeed. In this implementation guide for page loading, performance & speed, we’ll show you how to easily lazy load images & videos in WordPress.

Why Lazy Loading Matter?

The huge payload of a web page consists primarily of images, scripts, stylesheets, fonts, and videos. However, images take up over 60% of the size of a typical web page. Images are also critical to the design of a web page, so it’s not like you can get rid of them.

Without optimization, the user’s web browser downloads all the resources before rendering a page ultimately. This leads to increased load times, which can draw people away. WooCommerce estimated that for every 100ms of page speed improvement, an e-commerce website can increase revenue by 1%.

In a scenario like that, doing whatever it takes to optimize your load times makes a lot of sense. And since images are the primary contributor to web page size, starting with them is a good idea. This is where lazy loading comes into play.

Benefits of Lazy Loading

  • Improved Page Speed: By loading only the visible content, lazy loading significantly reduces the amount of data transferred during the initial page load, resulting in faster page speeds.
  • Enhanced User Experience: Faster page loads mean users can interact with your site more quickly, improving engagement and reducing bounce rates.
  • SEO Advantages: Page speed is a ranking factor for search engines like Google. Implementing lazy loading can help improve your site’s SEO.

Implement Lazy Loading From Scratch

Let us first look at how to do this without using any plugins. This option is recommended for those of you who are comfortable with JavaScript. Ideally, the following steps need to be taken:

Prevent image loading during page load: When you specify the URL or path of the image in the src attribute of the <img> tag, the browser will download the image during page load. To prevent the browser from downloading the image, you need to specify the location of the image in the data-src attribute of the <img> tag instead.

Register event handler functions in JavaScript to check for elements on two events: loading and scrolling. When an element comes into the viewport, load the value of the data-src element into the src element, which triggers the browser to load the image. Robin Osborne has explained a simple implementation of this process, and the demo is available on CodePen.

Use the Intersection Observer API

The intersection observer API helps identify DOM elements in the viewport at any given time. This is a cleaner way of implementing lazy load without writing event handler functions. The number of lines of code to implement lazy load goes down considerably, too. However, browser compatibility remains an issue. Moreover, the Google Developers Blog explains the implementation of intersection observer API through this CodePen demo. In this implementation guide for page loading, performance & speed, we’ll show you how to easily lazy load images & videos in WordPress.

Use a JavaScript Plugin

The two options discussed above need intermediate-level knowledge of JavaScript. If you are looking for easier implementation of lazy loading without using a heavy plugin that puts load into the server, you can try the plain JavaScript plugin, bLazy.

The bLazy library at less than 2 KB puts no additional load on the payload while allowing you to handle lazy loading images easily. So, to use the bLazy library, you need to initialize <img> elements with the following attributes:

class: set the class of all <img> tags to b-lazy
src: link to the placeholder image
data-src: link to the image to load
data-src-small: link to the image to load on screens less than 420 pixels wide

Finally, you need to initialize the bLazy library in just a few lines of code and all your images will be through lazy loading.

<script src=”blazy.js”></script>
<script>
;(function() {
// Initialize
var bLazy = new Blazy();
})();
</script>

Using a WordPress Lazy Loading Plugins

All these plugins will handle lazy loading for you automatically. Each also comes with some nice side features. For example, Lazy Load by WP Rocket also lazy loads of YouTube videos and replaces them with a thumbnail.

Optimole, the newest addition to the ThemeIsle family, also gives you rock-solid image optimization (as tested here) with quite advanced features in that regard. For instance, it gives you dynamic resizing based on the user’s screen size. Image optimization & Lazy Load by Optimole Image optimization & Lazy Load by Optimole. Like with most plugins, to get lazy loading, just install the plugin and enable the feature in the plugin’s control panel:

WordPress Lazy Loading Implementation Guide: Enhance Your Website’s Speed and User Experience

In today’s fast-paced digital world, website speed and performance are not just important; they are essential. A slow-loading site can significantly affect user experience, SEO rankings, and conversion rates. One effective way to boost your site’s speed is through lazy loading. This guide will walk you through the process of implementing loading feature on your WordPress site, enhancing both speed and user experience.

What is Lazy Loading?

Lazy loading is a technique designed to optimize website performance. Instead of loading all the content and media files at once when a page is accessed, lazy loads only the content necessary for the visible part of the page. As the user scrolls, the rest of the content is loaded progressively. This reduces initial page load time, saves bandwidth, and improves overall user experience. In this implementation guide for page loading, performance & speed, we’ll show you how to easily lazy load images & videos in WordPress.

Benefits of Lazy Loading

  • Improved Page Speed: By loading only the visible content, lazy load significantly reduces the amount of data transferred during the initial page load, resulting in faster page speeds.
  • Enhanced User Experience: Faster page loads mean users can interact with your site more quickly, improving engagement and reducing bounce rates.
  • SEO Advantages: Page speed is a ranking factor for search engines like Google. Implementing lazy loading can help improve your site’s SEO.

Implementing Lazy Loading in WordPress

WordPress has made it easier than ever to implement lazy load, thanks to its built-in feature introduced in WordPress 5.5. This feature automatically applies lazy loading to all your images and iframes. However, for more control and to lazy load other elements, you might consider using plugins or custom code.

Using WordPress Built-In Feature

If you’re running WordPress 5.5 or later, lazy loading for images and iframes is already enabled. WordPress adds the ‘loading=”lazy”‘ attribute to img and iframe tags by default. For most users, this means no further action is required unless you need more customization.

Other WordPress Plugins

For those seeking more control or looking to lazy load additional content types, several WordPress plugins can help:

  • a3 Lazy Load: Highly customizable, a3 Lazy Load allows you to lazy load images, iframes, and videos across your site, with options for mobile devices.
  • Lazy Load by WP Rocket: Created by the developers of the famous WP Rocket caching plugin, this lightweight plugin focuses on images and iframes, ensuring compatibility with WP Rocket’s caching features.
  • Smush – Lazy Load Images, Optimize & Compress Images: Smush combines lazy loading with image optimization, offering a comprehensive solution for improving page speed.

Best Practices

  • Test Performance: Before and after implementing lazy load, use tools like Google PageSpeed Insights to measure the impact on your site’s performance.
  • Monitor User Experience: Ensure that lazy loading does not negatively affect the user experience, particularly on mobile devices where scrolling is more prevalent.
  • Keep Accessibility in Mind: Ensure that lazy load implementations do not hinder the accessibility of your content, especially for users relying on assistive technologies.

Conclusion

Implementing lazy loading on your WordPress site can significantly enhance your site’s speed, user experience, and SEO. Whether you opt for the ease of WordPress’s built-in feature, the flexibility of plugins, or the customization potential of custom coding, lazy loading is a powerful tool in your website optimization arsenal. By following the steps and best practices outlined in this guide, you can efficiently implement lazy loading and enjoy the benefits of a faster, more engaging website.