Web Development

How to Optimise the Website Performance with Lazy Loading

Published: 7th July, 2023

Arunav Goswami

Data Science Consultant at almaBetter

Unlock the power of lazy loading to optimize website performance. Speed up load times, enhance user experience, and boost conversions for your online success.

Did you know that a mere one-second delay in website loading time can lead to a significant drop in user engagement and conversions? In today's fast-paced digital landscape, where attention spans are fleeting, optimizing website performance has become crucial for retaining visitors and achieving online success. One effective technique that has gained prominence in recent years is lazy loading. Using the lazy loading strategy, non-essential resources like photos, movies, and scripts are loaded only when they are required. Website owners can drastically reduce page load times and improve user experience by adding lazy loading. This post will explain the idea of lazy loading, when to use lazy loading, and give you useful advice on how to use it to enhance the functionality of your website.

Lazy loading for images

Lazy Loading Techniques

What is lazy loading?

Lazy loading is a method that defers the loading of certain webpage elements until they become visible to the user. It specifically targets non-essential items, such as images and videos, while prioritizing the loading of critical elements like text and page structure. It can be done using a variety of techniques, including JavaScript libraries, browser APIs, and CMS plugins. By prioritizing the loading of essential content, lazy loading reduces initial load times, maximizes resource usage, and ultimately enhances user experience.

Implementing Lazy Loading for Images

image1 (1).png

Lazy loading for images

Setting the initial image source attribute (src) to a placeholder or a scaled-down version of the picture enables lazy loading for images. The data-src attribute contains the URL for the actual image. The placeholder is replaced with the actual image when the user scrolls and it appears in the viewport, speeding up page load time and enhancing performance.

Here’s how you can do it:

  • To enable lazy loading for images, use JavaScript libraries such as LazyLoad, Intersection Observer API, or jQuery Lazy.
  • A placeholder picture or a scaled-down version of the image should be the value for the image source (src) attribute at first.
  • To store the URL for the actual image that will be loaded when it appears on the screen, use the data-src attribute.
  • Replace the placeholder picture with the actual image by updating the src attribute when the user scrolls and an image appears in the viewport.
  • To further increase loading speed, optimise the image's size and format. Utilise methods for image compression and offer images in contemporary formats like WebP.

Lazy Loading Videos

The linked video player is first replaced with a thumbnail or preview picture when a video is lazy loaded. When a user clicks on the thumbnail or it appears in the viewport, the actual video player and playback are loaded and started. This strategy greatly decreases page weight and accelerates loading time, improving user experience.

Implementing lazy loading for videos to improve website performance:

  • Avoid having videos slow down page loads by embedding them utilizing lazy loading techniques.
  • Implement lazy loading for YouTube or Vimeo videos by using libraries like LazyYT.js or Lazyframe.
  • First, replace the embedded video player with a preview image or a thumbnail.
  • Only when the user clicks on the thumbnail or when it appears in the viewport should the video player be loaded and playing initiated.

This method greatly minimizes the size of the page and speeds up the loading of your website.

Lazy Loading for Scripts and Widgets

The goal of lazy loading for widgets and scripts is to prioritize loading crucial scripts for initial page rendering while postponing loading non-critical ones. Techniques for asynchronous or deferred script loading can be used to avoid interfering with rendering. Conditional loading enables scripts and widgets to load dynamically only when required, improving the overall performance of websites. You can speed up page loads, use fewer resources unnecessarily, and improve user experience by adding lazy loading for scripts and widgets.

Implementing lazy loadings for scripts and widgets in the following ways:

  • Delay loading of non-critical scripts in favor of loading critical scripts that are needed for initial page display.
  • Use postponed or asynchronous script loading strategies to avoid delaying the rendering process.
  • Use conditional loading for any scripts or widgets that are only required during particular user interactions or on particular web pages.
  • To dynamically load scripts and widgets when they are required and improve overall efficiency, use lazy loading plugins or custom code.

Lazy Loading for Infinite Scroll and Pagination

It is useful to use lazy loading for infinite scrolling and pagination to improve website speed. Additional content is loaded dynamically as the user scrolls to the bottom of the page or clicks on pagination links, as opposed to loading it all at once. By enabling seamless and uninterrupted scrolling or browsing, this strategy reduces initial load times and enhances the overall user experience. You may guarantee a seamless transition between pages or new content sections while lessening the server load by using AJAX or Fetch API queries to fetch and render more content. Users receive visual feedback through loading spinners or indications during the content retrieval process, which increases their interaction with your website.

Here’s how you can implement it:

  • Lazy load more content when visitors hit a pagination link or scroll to the bottom of the page.
  • For a seamless user experience, load new content via AJAX or Fetch API queries.
  • To give users feedback, display a spinning or loading icon while retrieving and rendering the extra material.
  • To reduce wait times and ensure seamless scrolling and browsing, optimize the data retrieval and rendering processes.


In conclusion, optimizing website performance is crucial for online success and providing a positive user experience. Lazy loading strategies, such as prioritizing crucial elements and loading non-essential resources only when needed, can significantly improve website speed. By utilizing the available tools, APIs, and plugins for lazy loading, you can implement these techniques effectively. Remember to optimize your images, utilize modern formats, implement lazy loading for videos, prioritize essential scripts, and incorporate lazy loading for infinite scroll and pagination. These techniques will result in faster and more engaging user experiences, boost your search engine rankings, and ultimately increase conversion rates.

Read our recent blog on "Rise of No Code Tools: Empowering Creativity and Efficiency".

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Frequently asked Questions

Q1: What is lazy loading?

Ans: Lazy loading is a technique to improve website performance by deferring the loading of non-critical resources, such as images, videos, or scripts, until they are needed. It allows the initial page load to be faster by only loading the content that is visible to the user, and then loading additional content as the user scrolls or interacts with the page.

Q2: How can I implement lazy loading for images?

Ans: Implement lazy loading for images by using JavaScript libraries like LazyLoad, Intersection Observer API, or jQuery Lazy. Set a placeholder image initially and replace it with the actual image when it appears in the viewport.

Q3: How does lazy loading benefit website performance?

Ans: Lazy loading improves website speed by reducing initial load times and prioritizing the loading of essential content. It enhances user experience, increases engagement, and can lead to higher conversion rates.

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