What Is Largest Contentful Paint and How to Improve It

Largest Contentful Paint (LCP) is a Google user experience metric introduced back in 2021 as a part of the Page Experience Update. LCP is one of the three Core Web Vitals metrics. Largest Contentful Paint measures how long it takes for the largest above the fold element to load on a page. The types of elements considered for Largest Contentful Paint are:

• Images
• Image tags
• Video thumbnails
• Background images with CSS
• Text elements

Reducing your website’s LCP helps users see the essential content on your website faster. However, before you can fix potential LCP issues, you need to know how fast the largest element loads.

How to improve LCP?

1. Image compression

Compression means applying different algorithms to remove or group parts of an image, making it smaller in the process. Lossy compression removes parts of data from the file, resulting in a lower quality, lightweight image. JPEG and GIF are examples of lossy image types. Lossless compression maintains roughly the same image quality, i.e., it doesn’t remove any data. It produces heavy, high-quality images. RAW and PNG are lossless image types.

2. Choosing the right format

The tricky thing about choosing between image formats is finding a balance between quality and speed. High-quality images are heavy but look great. Lower-res ones look worse but load faster. In some cases, high-resolution images are necessary to stand out from the competition. Think photography and fashion sites. The choice here depends on your personal needs. Again, you have to run tests to see how much image quality affects your visitor’s behavior.  For an optimal balance between quality and UX, use WebP while keeping the original format as a backup since WebP doesn’t have 100% browser support.

3. Use the srcset attribute

A classic mistake when working with images is serving one large image to all screen sizes.  Large images look good on smaller devices, but they still have to be processed entirely. That’s a massive waste of bandwidth.  Provide different image sizes and let the browser decide which one to use based on the device. To do that, use the srcset attribute and specify the different widths of the image you want to serve.

4. Preload Hero Images

This final tip is about optimizing how fast the browser discovers hero images. Hero images are usually the most meaningful above the fold elements, so loading them faster is crucial for the user experience. This technique tells the browser to prioritize that specific image when rendering the page. Since browsers discover these images late, using link rel=preload can improve both actual and perceived performance.

5. CSS and JavaScript Optimization

Before the browser can render a page, it has to load, parse and execute all CSS and JavaScript files it finds while parsing the HTML. That’s why CSS and JavaScript are both render-blocking by default.  Minification removes unnecessary parts from code files like comments, whitespace, and line-breaks. It produces a small to medium file size reduction. On the other hand, compression reduces the volume of data in the file by applying different algorithms. It typically produces a huge reduction in file size. Both techniques are a must when it comes to performance.

Conclusion

Largest Contentful Paint is a vital metric for understanding and improving the perceived load speed of a webpage. By focusing on LCP, developers can enhance user experience, improve SEO rankings, and boost conversion rates. As the web continues to evolve, staying vigilant about performance metrics like LCP will be key to long-term success.

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