Largest Contentful Paint

Definition

Largest Contentful Paint (LCP) is a web performance metric that helps web-based applications measure page load time. LCP measures the time at which the largest visible content of a page is displayed on the screen.

Advantages

LCP is a simple and efficient way to measure page load time. It provides a clear measurement of performance and can help to see the progress of page loading faster.

Disadvantages

Because LCP measures only the largest visible content, it can impact the performance of websites that contain a lot of smaller content. It can be difficult to figure out which content is the "largest," and it can lead to incorrect results.

Use cases

LCP is best for measuring the performance of pages that contain many images or videos. It is also useful when you want to know how fast a page loads and how much time server rendering takes.

15 Reasons for High Largest Contentful Paint Values:

1. Long loading of resources: If resources such as images, videos, or fonts take a long time to load, this can cause loading to lag.
2. Unoptimized images: If images are not optimally compressed, this can cause them to take longer to load and thus delay loading.
3. Poor network connection: If a user has a slow or poor internet connection, this can cause resources to take longer to load and delay the LCP.
4. Blocking Resources: When resources such as scripts or Stylesheets block the rendering of the page, this can delay the LCP.
5. High server response times: If the server response times for a request are high, this may cause the LCP to delay.
6. Too many parallel requests: If a page sends too many parallel requests at once, this can cause resources to take longer to load and delay the LCP.
7. Unoptimized code: If a page's code is not written optimally, this can cause resources to take longer to load and delay the LCP.
8. Dynamic content: If a page contains a lot of dynamic content that is loaded only on request, this can cause the LCP to lag.
9. Third Party Resources: If a page uses a lot of third-party resources, this can cause those resources to take longer to load and delay the LCP.
10. Problems with the Caching: If a page is not cached properly, this can cause resources to have to be loaded over and over again and delay the LCP.
11. High JavaScript-Execution time: When one side much JavaScript that takes a long time to run, this may cause the LCP to delay because the JavaScript blocks the rendering of the page.
12. Unnecessary resources: If a page contains resources that are not required to render the page, this can cause these unnecessary resources to be loaded and delay the LCP.
13. Delayed redirects: If a page contains redirects that take too long, this can cause the LCP to lag.
14. Unoptimized database queries: If a page contains many database queries that are not optimally written, this can cause these queries to take a long time and delay the LCP.
15. Problems with the CDN (Content Delivery Network): If a site has problems with the CDN, this can cause resources to not load fast enough and delay the LCP.

How to improve your LCP value

A good LCP value contributes to improving the user experience and indirectly to the Search engine optimization at. An ideal LCP value should be within 2.5 seconds or faster. Here are some methods to improve the LCP value of your website:

Optimize images

• Compress imagesUse tools like ImageOptim or TinyPNG to reduce the file size of the images.
• Lazy Loading: Load images only when they are in the user's visible area to speed up the initial loading process.
• Responsive images: Use the srcset-attribute to provide different image sizes for different screen resolutions.

Improve server performance

• Optimize server response times: Use fast hosting solutions and optimize the server, possibly with Caching.
• Content Delivery Network (CDN): A CDN can help deliver content to the end user faster.

Optimize CSS and JavaScript

• Minimize CSS and JavaScript defer load: Minimization and asynchronous or differential loading can improve loading time.
• Critical Path Optimization: Load only the necessary CSS and JS for the "above-the-fold" Content first and the rest later.

Text blocks and other elements

• Optimize fonts: Avoid blocking the display by loading web fonts and set font display: optional or font-display: swap.
• Avoid elements with large layout shifts: Prevent elements such as displays or Pop-ups negatively affect the LCP by defining their size and position in advance.

Tools and monitoring

• Use tools like Google PageSpeed Insights, Lighthouse or WebPageTest to measure the LCP value and get specific recommendations.

With these methods, you can systematically improve the LCP value and thus not only optimize the user experience, but also the Ranking of your website in the search results positively. However, it is important to perform regular audits, as both website content and Google algorithms are constantly changing.

Images can be problematic for LCP assessments

Web publishers often upload images in their original size and then use HTML or CSS to resize the image to display in a smaller version.

The original size is what Google calls the "intrinsic" size of the image.

If a publisher uploads an image with a width of 2048 pixels and a height of 1152 pixels, these 2048 x 1152 pixels height and width are considered the "actual" size.

If the provider now reduces the 2048 x 1152 pixel image to 640 x 360 pixels, the 640×360 image is called the viewable size.

For the calculation of the image size Google uses the smaller size between the actual and the visible size of the image.

It is possible to achieve a high score for the largest content-rich image with a large image that has been reduced in size using HTML or CSS. However, it is best if the actual size of the image is the same as the visible size.

The image will download faster and your Largest Contentful Paint Score will increase.

Beware of these "traps" when awarding points

All elements that appear on the user's screen (the Viewport) are used to calculate the LCP. This means that images that are rendered off-screen and then move into the layout once they are rendered are not included in the score for the largest content-rich image.

Conversely, elements that initially appear in the Viewport of the user and then moved out of the screen are included in the LCP calculation.

Conclusion

The Largest Contentful Paint, LCP for short, is much more than just a technical indicator for web developers. It reflects the quality of the user experience and can therefore have a significant impact on the SEO performance of a website. A fast LCP under 2.5 seconds signals that the most important content on the page is loading quickly, which increases the likelihood that users will stay on the site and interact. This is especially important at a time when user expectations for fast and efficient websites are steadily increasing.

By optimizing images, server performance, and code, you can significantly improve the LCP. For example, consider an online magazine that contains numerous high-resolution images. Reducing the file size through compression could speed up the LCP tremendously, which in turn increases reader satisfaction and lowers the bounce rate. Similar improvements can be achieved by minimizing CSS and JavaScript can be achieved. An online store could benefit from this, as product images and descriptions load faster, which can lead to more sales.

But caution is advised: Optimizations should be carefully implemented and tested to avoid unwanted side effects. For example, overly aggressive lazy loading of images can cause the user to encounter empty placeholders when scrolling.

Tools like Google PageSpeed Insights or Lighthouse provide valuable insight into LCP and other webitals metrics and should be used regularly to measure the impact of changes.

Overall, the LCP is a powerful metric that has a direct impact on user experience and thus SEO success. It should not be considered in isolation, but it does provide an important guide for overall website optimization.