What Is Lazy Loading

What Is Lazy Loading? A Clear Concept

A clear concept about what is lazy loading. How to improve site loading speed applying lazy loading technique. What are the recommended image lazy loading plugins and more?

Lazy loading is a technique in which the images, video, and other media files are loaded only when required (in this case page is scrolled down to the image).

Lazy loading was popularized by Google. Google has it implemented on their most of the high traffic website that they own.

It is actually a great way to improve the performance of your website for your users.

This is a better way of implementing dynamic loading of resources than preloading because it’s lazy in nature and only loads the assets when required.

When you scroll down the page, the media files are loaded and images in particular. This reduces the initial page load time significantly by reducing the number of requests made for HTML, CSS, and JavaScript resources.

Lazy loading images can always be implemented using 3rd party plugins, but it is actually pretty simple to implement on your existing website if you are comfortable with HTML/CSS code.

Why should I add lazy loading to my site?

For a long time, loading all elements on the page in parallel was the best practice. But today it’s very common for users to have limited connectivity and fast mobile networks.

For this reason, it’s a good idea to load only what you need at first, and then load additional resources later when they are needed.

Lazy loading can also reduce the amount of work that needs to be done by the browser at page load time. This ultimately means that you’ll get a faster page load for the user.

What Is Lazy Loading? A Clear Concept 1

You can many ways to Implement lazy loading on your website. Like any technique, there are some pros and cons associated with each method.

How to add lazy loading in WordPress Site?

You can add lazy loading to any website with some simple additions of CSS and JavaScript code. All you need is a bit of HTML tagging, too.

But in this post, I’ll talk about only WordPress lazy loading plugins that let you enjoy the advantages of lazy loading images on a WordPress site.

How to add lazy loading Using Plugin?

There are many WordPress plugins available that will add lazy load functionality automatically to your website with one click.

If you want to increase overall site loading time, I’ll recommend the Permatters speed optimize plugin. This plugin will optimize your website for better user experience and performance. It also has a few additional features such as lazy loading, gzip compression, etc…

perfmatters lazy load
Permatters Lazy Load Option

If you want to get hands dirty with code or have some advance requirement then I will recommend other following plugins.

WP Rocket is one of the most popular WordPress cache plugins. It’s also the most popular plugin for lazy loading images. It’ll help you reduce load speed and increase total pageviews. You can read WP Rocket Review.

wp rocket image lazy load
WP Rocket Lazy Load Option

You can also use the Light Speed Cache plugin which is another popular plugin among WordPress users. It enables you to use advanced caching rules for your website which helps in improving page loading time and reduces bandwidth usage as well.

lazy load by litespeed cache
LiteSpeed Cache Lazy Load Option

Besides, the above plugins help to load iFrames. I recommend you these plugins for that.

Lazy loading vs dynamic loading vs JavaScript preloading vs Eager lazy loading

The big difference between the four terms is what happens when a user first visits your site.

Lazy loading: With lazy loading, resources are loaded as required (as the name suggests). This means that depending on the users’ actions, certain elements might not be loaded at all.

Dynamic loading: With dynamic loading, you’ll have to preload everything – even if it’s not required. So depending on how much data you have to send, this might increase the page load time significantly – even if some of that content is never viewed by anyone.

JavaScript preloading:

JavaScript Preloading is an important part of the image lazy load process. It facilitates browser cache by delivering HTML (and CSS if you are using a style-based solution).

It uses AJAX to deliver a separate file for each image on your page. This allows browsers to start downloading images before they have been fully loaded, thus increasing the number of images that can be loaded over a slow network connection or with a slow client computer.

Eager lazy loading: This is similar to lazy loading, and you’ll load resources as needed. The difference is that with the eager method, you don’t have to worry about whether or not something is visible right now. If it’s loaded already, well and good – otherwise just load it when it becomes necessary.

Understanding Lazy Loading for SEO

Some people have concerns that lazy loading images will negatively impact an SEO’s ability to access its content.

Google does a great job of caching the resources on your website whenever it crawls it, so if you load elements in a way that remains fast over time and doesn’t change too often, I don’t think anyone should worry about affecting their search engine rank.

Lazy Loading and CDN

There are some useful CDN in the industry that can help you to distribute your image and media files. Most of these services provide a great user experience by implementing lazy loading functionality for you.

Cloudflare CDN is one which I would like to highlight among other CDN services.

Cloudflare is a content delivery network that offers free & paid CDN for all its account users. It also optimizes your website and improves security by implementing some advanced strategies like Page speed optimization, HTTP/2, and many more. It also helps you to lazy load your website image and media files.

lazy Loading In Desktop or Mobile: How it impacts Google SEO?

Lazy loading has been around on desktops for a long time. It’s a feature that’s available in most major browsers, but there are some features – like preloading and partial loading – which aren’t available to all browsers.

With mobile devices though, lazy loading is something you’ll need to pay attention to.

It’s important that you think of it as an SEO ranking factor because Google is now paying attention to lazy loading images on mobile devices.

The key here is not to just implement lazy loading, but also to make sure it loads resources in a fast and efficient way. If it doesn’t, there’s a chance your search engine rank would be negatively affected.

Lazy loading image in different size

Another reason why you should focus on lazy loading images is because of the increased mobile usage.

People like browsing and searching with their phones, but they’re not as fast or accurate when it comes to clicking links, so having larger images means people will likely click away before the full image loads.

So having smaller images is obviously going to be better for mobile devices, even if it means more data needs to be loaded, it’s worth it in the long run because people will click through rather than leave your website altogether.

What Frameworks are used in lazy load?

There are a few options available to you:

1. Picturefill (by default use)

Picturefill is a script that provides lazy loading functionality for your images. This lightweight JavaScript library will work with almost all of the major browsers and it’s also responsive. So it’ll change its behavior depending on what kind of device you’re using.

2. LazyLoadJS (by default use)

LazyLoadJS is a script that provides lazy loading functionality for your images and it’s very lightweight and works with all the major browsers. So you don’t have to worry about any issues when using it.

It also features multiple queues in order to improve the overall performance of your website and it’s very easy to use – developers of all skill levels should have no problem using it.

3. LoadCSS (by default use)

LoadCSS is a script that provides lazy loading functionality for your stylesheets, unlike other libraries which only work with images or video files. This will also preload HTML and JavaScript.

4. SlimerJS (not available)

SlimerJS is a script that provides lazy loading functionality for your images and it doesn’t use any JavaScript libraries, but it does have its own API which you can use to configure the way your image lazy load works.

It’s also very lightweight and fast, so it won’t impact your website performance in any way.

Is lazy loading work in background images?

Yes, it would work in background images.


Lazy loading is one of the most underused performance optimization techniques when it comes to WordPress and websites in general.

It’s very easy to implement once you know how, but not many people even know about it. If you want to improve your page load speed then I will highly recommend you to implement lazy loading for image and media files.

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  • Sonya Sultana

    Sonya Sultan is a content writer for WordPress and small businesses. She has been writing content since 2020 with full energy & passion. When she has free time, she watches her favorite TV shows and reads novels.

    [email protected] Sultana Sonya
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