Can Lazy Load Plugins Really Speed up Your Site Loading? Comparison of Popular Plugins

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Lazy Load is a technique for loading images during page scrolling. When the images are not visible, they are not loading.

If you are good at coding, adding the Lazy Load support directly in your theme is not a problem; however, it is much easier to use a small ready-made plugin.

Such a plugin is considered to increase site loading speed. Let’s check it by putting it into practice.

You can find about 10 plugins for image lazy loading in the WordPress repository. Plugins that have a lower user rating for some reason or too low a number of active installs have been excluded. As a result, there are only three popular plugins for comparison: Lazy Load, Unveil Lazy Load, and Lazy Load XT.

Our recently published article with twenty unoptimized for that time images 1200 x 1200 pixels each was taken for a test.

We used Google’s PageSpeed Insights tool. After activating a new plugin, we completely emptied the cache and tested a fresh cached page. The test was taken 7 times for each plugin with a different time interval. The plugins were activated several times in random order to reduce the server response time error. Caching on the server is based on Nginx. CSS, JavaScript, and HTML compression is done using the Autoptimize plugin.

No plugin Lazy Load Unveil Lazy Load Lazy Load XT
Test 1 91 / 100 89 / 100 92 / 100 94 / 100
Test 2 93 / 100 89 / 100 89 / 100 94 / 100
Test 3 93 / 100 89 / 100 89 / 100 94 / 100
Test 4 93 / 100 89 / 100 89 / 100 94 / 100
Test 5 91 / 100 89 / 100 89 / 100 94 / 100
Test 6 93 / 100 89 / 100 89 / 100 94 / 100
Test 7 91 / 100 89 / 100 89 / 100 94 / 100
Average score 92.1 / 100 89 / 100 89.4 / 100 94 / 100

As can be seen from the test, the Lazy Load and Unveil Lazy Load plugins not only failed to increase the speed of site loading, but also lowered it instead; and the Lazy Load XT plugin increased the site loading rate by almost 2 points.

Lazy Load

60,000+ active installs

Loading speed average score: 89 out of 100

The Lazy Load plugin integrates the code written by several teams, including the WordPress.com VIP team. The plugin uses jQuery.sonar. The file size is 1.4 KB when compressed. The plugin does not require any configuring. Works for images in lists of posts, in articles, in widgets.

In our opinion, image loading is not smooth if the Internet connection speed is low.

Unveil Lazy Load

9,000+ active installs

Loading speed average score: 89.4 out of 100

The plugin uses light JavaScript Unveil.js with a size of 0.6 KB. Its parameters are similar to those of the previous one.

Lazy Load XT

1,000+ active installs

Loading speed average score: 94 out of 100

The Lazy Load XT plugin is the winner not only by the results of the load speed test, but also by the number of available options.

You can choose using Lazy Load for the thumbnails and avatars in the comments. The plugin can even use lazy loading for YouTube Vimeo videos.

You can also enable AJAX posts loading which is an important feature. With the other two plugins, images will not be displayed if new posts are loaded using AJAX.

The plugin showed the smoothest and fastest loading even at a low Internet connection speed. You can disable animations as well if you wish.

We recommend activating the two options, “Load minimized versions of JavaScript and CSS files” and “Load Scripts in the footer”. If you use Autoptimize or a similar plugin for JavaScript and CSS compression, using the first option is not necessary.

Using Lazy Load plugins does not greatly increase site loading speed but it improves site user experience. In order to optimize loading speed, we also recommend optimizing the images themselves using, for example, the EWWW Image Optimizer plugin.