What is Largest Contentful Paint (LCP) - a comprehensive guide 2024

Largest Contentful Paint, or LCP – an indicator that can tell a lot about the performance of your website. In short, LCP helps to understand how quickly the main content of the page becomes visible to the user.

Why is this important? Because the first impression is crucial for the further behavior of visitors – from keeping them on the site to conversion. Additionally, pages with better LCP not only encourage users to continue exploring the content but are also perceived better by Google's algorithms, which translates into higher positions in search results.

In this article, we will bring you closer to what exactly LCP is, why it's worth paying attention to, and how you can improve this indicator so that your website runs like a Ferrari.

LCP, or Largest Contentful Paint, is an indicator that measures the time from the start of the page load to the moment when the largest content element (it can be an image, text block, or other media) is displayed to the user.

In other words, it is the time that elapses before the user sees the "meat" of your page – the main content that is supposed to interest them. It is part of a larger family of Core Web Vitals from Google, which together give a picture of the quality of using a website.

Before starting the optimization of LCP, it is crucial to understand which aspects of your site most affect this indicator. LCP, as one of the Core Web Vitals, is closely related to the quality of use of your site by visitors.

So, before you start, think about which element of your site is the "largest" and most significant - it could be a large image, video, or a large text block. Identifying this element is the first step to effective optimization.

Tools for Measuring LCP

To measure LCP and identify areas for optimization, you can use several online tools:

When using these tools, pay special attention to the resources that are loaded before the "largest content element." Often, these are CSS and JavaScript resources that can be optimized to speed up loading time.

Optimal LCP Values

Every site should aim to achieve an LCP time of 2.5 seconds or faster. According to recent data, only about 25% of sites meet this requirement, which means many websites have room for improvement in this area.

Sites that achieve better LCP scores not only offer better user experiences but can also enjoy better positions in Google search results.

Considering the overall web, less than a quarter meet the requirements for optimal LCP. This means improving this indicator can give your site a significant competitive edge, both in terms of UX and SEO.

Large images or media without proper optimization

Unoptimized images are one of the main culprits of slow LCP. Common mistakes include:

How to fix it: Use online image optimization tools or CMS plugins that automatically adjust the size and format of images to user needs. Consider using image formats like WebP, which provide high quality at a lower data volume.

CSS and JavaScript Resources That Block Rendering

Scripts and stylesheets loaded in the page header before the content is loaded can significantly slow down LCP.

How to fix it: Use async or defer for JavaScript scripts to allow asynchronous or deferred loading of scripts. Try to minimize the amount of CSS loaded in the head section of the page, moving non-critical styles to the bottom of the code or loading them only when needed.

Server Response Time That Is Too Slow

The server's response time affects every element of your site, including LCP. Slow servers can delay everything from the start.

How to fix it: Optimize your server by improving configurations, using fast server technologies, and check if your hosting is fast enough. Consider using a Content Delivery Network (CDN) to reduce server load and speed up content delivery to users worldwide.

Here are some advanced strategies to help you improve LCP, making your site faster and more responsive.

Image Optimization

High-quality images are essential for an attractive site but can significantly affect LCP if not properly optimized.

Use tools like TinyPNG or ImageOptim to reduce image size without losing quality. These tools automatically remove unnecessary metadata from images and apply advanced compression techniques, reducing file size, which speeds up page loading time.

Ensure all images are lazily loaded (lazy loaded), especially those below the fold. Lazy loading means that images are loaded only when they are close to entering the user's screen, reducing the amount of data loaded initially and speeding up LCP.

Resource Prioritization

Not all resources on your site are equally important. Some need to be loaded immediately for the page to display correctly, while others can wait.

Use <link rel="preload"> for key CSS or JavaScript files to indicate to the browser which files should be loaded first.

Chrome DevTools is a powerful tool that can help you identify which resources are critical for quick content display.

Removing Render-Blocking Resources

Extraneous CSS and JavaScript, especially those loaded in the <head> section of your page, can significantly delay the moment when the user starts to see the content of the page. This is because the browser needs to download and process these files before displaying anything to the user.

Tools like PurifyCSS or UnCSS analyze your pages and help remove all unnecessary styles and scripts that are not used on a given page.

By removing these excess resources, you can reduce the page loading time by even 20-30%, significantly improving LCP. On average, pages can save several seconds on loading time, which is crucial for maintaining user attention and improving the overall experience.

This optimization involves analyzing CSS and JavaScript code and removing everything that is not directly used on the page.

For example, if there is a script on your site that handles a contact form, but it is only on one subpage, there is no need for it to be loaded on every page of the site.

Implementing Lazy Loading

Lazy loading, a technique of delayed loading of resources such as images or iframes until they are needed (e.g., when the user scrolls towards them), is a powerful method to speed up the loading of the visible part of the page.

Using the HTML attribute loading="lazy" for images and iframes is the simplest way to implement this technique, as it allows the browser to decide when resources should be loaded.

For instance, if a page contains a large number of images, lazy loading can reduce the initial loading time by 50-70% , as these resources are loaded only when necessary, instead of all at once at the beginning.

This not only speeds up LCP but also reduces data usage for users on mobile devices.

For older browsers that do not natively support loading="lazy" , you can use a JavaScript library like lozad.js, which emulates this behavior. It works by monitoring whether an element (e.g., an image) is close to entering the screen and then initiates its loading only then. This smart approach to resource loading allows for a significant improvement in page loading speed without the need for extensive changes to its structure or content.

External factors can significantly influence the loading speed of your page, and consequently, LCP. Here are some of the key variables along with their potential impact:

The most critical of these factors are server performance and the stability of the internet connection, which can have a direct and significant impact on LCP. External scripts, though important, are often harder to control, but their impact can also be minimized through appropriate optimization strategies.

Advanced LCP optimization requires deeper technical knowledge but can bring significant benefits to your site's performance. Here is a list of techniques that can be applied:

The most important of these techniques are dynamic imports and the use of HTTP/2, which can have a direct and significant impact on the page loading speed. Precompiling and minifying as well as using Cache-Control are also important, but their impact will be more noticeable in the long term and in the context of the overall performance of the site.

Improving LCP may require some technical skills, but the benefits of a faster, more responsive site are invaluable. Not only will you improve the user experience, but you could also potentially improve your positions in search results. Start by applying these tips, and your website will be well on its way to achieving – and even exceeding – optimal LCP values.