Enhancing Largest Contentful Paint For Faster Site Performance

Largest Contentful Paint (LCP) is a Core Web Vitals metric that measures how long it takes for the largest element to become visible in the viewport. LCP is important for user experience and SEO performance. A good LCP value is 2.5 seconds or less, and sites should aim for at least 75% of page visits to be under this threshold. To improve LCP, you can reduce the Time to First Byte (TTFB) of your server response, use image compression, and employ font loading techniques. Additionally, using a Content Delivery Network (CDN) can help improve LCP by delivering content from a location closer to the user.

Reduce the time taken to load the largest content element

Improving the Largest Contentful Paint (LCP) score is essential for performance, user experience, and SEO. LCP measures how long it takes for the largest element, usually an image or text block, to become visible to the user. A good LCP value is considered to be 2.5 seconds or less, with anything above 4 seconds considered poor.

One of the main reasons for a poor LCP score is a slow server response time. This can be improved by reducing the Time to First Byte (TTFB), which measures how long it takes for the browser to receive the first byte of content from the server. Minimising the number of redirects a visitor must wait through can help speed up TTFB. Additionally, enabling page caching can improve site speed by storing pages as HTML files on the server after the first load.

Another factor affecting LCP is the size of the content. Large JavaScript files, for example, can increase page load time. To improve this, you can reduce the size of the JavaScript file by minifying it or splitting it into smaller files. Alternatively, you can demand-load assets as you need them, rather than including them all at once.

Optimising the LCP element's priority can also help improve LCP. Setting a high priority on the LCP element will ensure it loads first, but setting a high priority on too many elements will reduce the effectiveness of this strategy. Similarly, lowering the priority of images that are not immediately visible can afford more bandwidth to the LCP element.

It is important to note that improving LCP often requires optimising the entire loading process, rather than a quick fix to a single part of the page.

Optimise images and use modern formats

Images are often the biggest bandwidth hogs and can be responsible for slowing down your Largest Contentful Paint (LCP) score. This is because images are usually found in above-the-fold content, so they are important to optimise for the web.

To optimise your images, you should use the right type, compress them, and ensure they are properly sized. Using the correct image format will reduce the extra bloat your browser will have to download, aiding in a faster LCP score. For example, JPEG or JPG refer to the same image format.

Modern image formats like WebP and AVIF are recommended as they offer good compression and can reduce image file sizes while maintaining quality. WebP is widely supported, and AVIF is a newer format with even better compression. Using the Squoosh web app, you can convert your images to these formats and achieve significant file size reductions.

It is also important to serve responsive images to save bandwidth. You can use preload and fetchpriority to prioritise key images, and lazy load images below the fold to reduce network contention. Additionally, you should avoid request chains that delay image loading. A request chain happens when one or more resources outside of the main HTML have to load before another request can start. For example, if your JavaScript loads an image, the browser must first download the HTML, then the JavaScript, and then start downloading the image, creating a chain that delays the image load.

Reduce the number of redirects

Reducing the number of redirects is an important step in improving the Largest Contentful Paint (LCP) of your site. LCP is one of the Core Web Vitals metrics and it measures how quickly the main content of a web page is loaded. It specifically calculates the time from when a user initiates loading a page to when the largest image or text block is rendered within the viewport.

A good LCP value is considered to be 2.5 seconds or less, and this should be achieved for at least 75% of page visits. However, it is rare that a quick fix to a single part of a page will significantly improve LCP. Instead, the entire loading process needs to be optimized.

One of the main factors that affect LCP is the Time to First Byte (TTFB), which measures the time it takes for a browser to receive the first byte of content from the server. A high TTFB can make it challenging or even impossible to achieve a 2.5-second LCP. Multiple redirects can cause a slow TTFB, even on otherwise fast sites. This often happens when visitors arrive through advertisements or shortened links, which are common in paid campaigns. Each redirect adds to the time it takes for users to reach your site, impacting their experience.

To reduce the number of redirects, you should ensure that your landing page is simple and well-optimized. This will help engage users as quickly as possible, even if they have to wait through a redirect. Additionally, consider using Content Delivery Networks (CDNs) to serve your content faster to regions with slower internet connections. Simplifying your UX and web design can also help reduce the number of redirects and improve your LCP.

By minimizing the number of redirects, you can improve your TTFB and, consequently, your LCP score. This will enhance the user experience and ensure your site performs well in terms of SEO and page speed grade.

Improve server response time

Improving your server response time is one of the most important steps in improving your Largest Contentful Paint (LCP) as it directly affects every step that comes after it. A good server response time, also known as Time to First Byte (TTFB), should be under 200 ms.

TTFB measures how long it takes for a browser to receive the first byte of content from the server. A large delta between TTFB and First Contentful Paint (FCP) could indicate that the browser needs to download a lot of render-blocking assets. It can also mean that the browser has to complete a lot of work to render any meaningful content, a classic sign of a site that relies heavily on client-side rendering.

To improve your server response time, you can:

• Enable page caching: This will store your site's pages as HTML files on the server after the page is loaded for the first time, so that the content will be displayed faster.
• Use a Content Delivery Network (CDN): A CDN is a network of servers around the world that host some or all of your pages. This reduces the impact of geography on site speed and allows your web hosting to handle a significantly higher volume of simultaneous visitors. Cloudflare, for example, is one of the biggest CDNs with 160+ locations and they offer a free plan.
• Establish third-party connections earlier: This will improve your TTFB and also address the "Preconnect to required origins" PageSpeed recommendation.
• Increase your server capacity: If the above steps do not improve your response time, you may need to increase your server capacity to handle the number of requests coming in.

Use a content delivery network (CDN)

Using a content delivery network (CDN) can significantly enhance your website's performance and user experience. CDNs are distributed networks of servers and data centres that store and deliver content to users based on their geographic location. By employing a CDN, you can bring your servers closer to your users, reducing the time it takes for content to load.

Image Content Delivery Networks (Image CDNs) are a specialised type of CDN that focuses solely on optimising and delivering images. They store images in data centres worldwide and serve them responsively, taking into account the user's device and network conditions. This ensures that your images are delivered in the most optimal format, improving your website's loading speed.

When choosing an Image CDN, it's important to consider options like Image Engine and Image Kit. Image Kit, for instance, integrates with a CDN to deliver well-optimised images and basic videos quickly. It can transform images in real time, adapting them to various conditions, ensuring a seamless user experience.

Another popular choice is Optimole, a CDN designed primarily for WordPress. With data centres in over 200 cities worldwide, Optimole excels at improving server response times for images. It automatically optimises images based on your default settings, ensuring efficient and responsive image delivery.

While CDNs can greatly enhance performance, it's worth noting that using a third-party domain to host your images may introduce additional connection costs. To mitigate this, consider serving images from the same origin as your HTML document or utilising the proxy capabilities offered by many CDNs. By preconnecting to the origin, you can reduce these extra costs while still benefiting from the performance boosts that CDNs provide.

Frequently asked questions