WIP – Best Practices for Optimizing Core Web Vitals

Chris Morey 7 mins

Optimizing Core Web Vitals is critical for improving website performance and search engine rankings. To achieve this, businesses can follow best practices such as improving Largest Contentful Paint, optimizing First Input Delay, enhancing Cumulative Layout Shift, prioritizing mobile optimization, and monitoring ongoing performance.

In May 2021, Google officially rolled out an algorithm update that added Core Web Vitals as a ranking factor. This update emphasizes the importance of delivering a fast and user-friendly web experience. The Core Web Vitals are a set of metrics that measure the loading speed, interactivity, and visual stability of a website. Google considers these metrics as key indicators of the quality of the user experience.

To improve website performance and achieve a better ranking, website owners and developers must optimize their website for Core Web Vitals. In this article, we’ll explore some best practices for optimizing Core Web Vitals that can help your website load faster, be more interactive, and provide a better user experience. By following these practices, you can ensure your website meets the Core Web Vitals standards set by Google and improve your website’s search engine rankings.

Understanding Core Web Vitals

Core Web Vitals are a set of specific metrics that Google uses to measure and quantify the overall user experience of a web page. They are a set of metrics that include the following:

  1. Largest Contentful Paint (LCP): measures loading performance. It measures the loading time of the largest content element or image on the page. The optimum LCP score is underthan 2.5 seconds.
  2. First Input Delay (FID): measures interactivity response time. It measures the time taken between the first interaction of the user and the response from the browser. A perfect FID score is under than 100 milliseconds.
  3. Cumulative Layout Shift (CLS): measures visual stability. It measures how much the page layout shifts while it loads. The ideal CLS score is less than 0.1.

Together, these three metrics provide a comprehensive view of how quickly the page loads, how fast it responds to user input, and how stable and smooth the visual experience is.

Largest Contentful Paint (LCP)

Largest Contentful Paint (LCP) is one of the three Core Web Vitals that measures how quickly the largest content element of a page is loaded. This content element is usually an image or video, and its loading speed significantly impacts user experience. The faster the LCP, the quicker the website appears to load, which can positively impact user engagement and search engine rankings.

Optimizing LCP is essential to improving website performance. Here are some best practices to follow to optimize LCP:

  1. Reduce server response times: Server response time is the amount of time it takes for a server to respond to a browser request. Slow server response times can slow down the entire website, including LCP. To optimize server response times, reduce the size of your code and images, and leverage browser caching.
  2. Optimize images and videos: Images and videos are typically the largest elements on a webpage and can significantly impact LCP. Compress and optimize images, and use the most efficient video format for your website. Use lazy loading to only load images and videos as they become visible on the page.
  3. Leverage browser caching: Browser caching stores website resources like images, videos, and HTML files on the user’s device. When a user revisits a website, their browser can quickly retrieve cached resources, speeding up the page load time. Leverage browser caching to reduce the amount of data that needs to be downloaded by the user.

Here are some examples of websites that have improved their LCP by following these best practices:

  1. Web.Dev: Google’s Web.Dev has improved its LCP from 4.4 seconds to 1.4 seconds by optimizing images, leveraging browser caching, and minifying code.
  2. Wix: Website builder Wix has reduced its LCP by over 50% by optimizing images and reducing server response times.
  3. Neil Patel: Marketing expert Neil Patel has improved his LCP by over 70% by optimizing images and implementing lazy loading.

By optimizing LCP, you can improve user experience and positively impact search engine rankings. In the next section, we will discuss how to optimize the second Core Web Vital, First Input Delay (FID).

First Input Delay (FID)

First Input Delay (FID) is a measure of how long it takes for a page to become interactive, which is particularly important for sites with interactive elements like forms, buttons, or menus. FID is measured as the time between when a user first interacts with the page and when the browser responds to that interaction.

Why FID Matters

FID is crucial for user engagement and satisfaction since slow response times can lead to a poor user experience. A delay in the page’s interactivity can lead to frustrated users, who may abandon the page or even the entire site, which can have a negative impact on business metrics.

How to Optimize FID:

  1. Minimize JavaScript execution time: Reducing the time it takes for JavaScript to execute is a critical step in optimizing FID. JavaScript can block the main thread, delaying the page’s interactivity. You can identify problematic scripts by using tools like Chrome DevTools or Lighthouse.
  2. Remove third-party scripts: Third-party scripts are a common cause of slow page load times and FID delays. You can remove or defer them to improve FID.
  3. Optimize the browser main thread: The main thread is responsible for handling user inputs and executing scripts, which makes it a crucial part of page interactivity. You can optimize it by minimizing the impact of long-running scripts, reducing the number of requests and downloads, and deferring the loading of non-critical resources.

Real-world Examples:

  • Slack managed to reduce their FID from 300ms to 50ms by optimizing their JavaScript execution time and deferring the loading of non-critical resources.
  • The New York Times reduced their FID from 300ms to 150ms by deferring the loading of third-party scripts and optimizing their JavaScript execution time.

By optimizing FID, you can significantly improve your users’ experience, leading to increased engagement and potentially higher business metrics.

Cumulative Layout Shift (CLS)

Cumulative Layout Shift (CLS) measures the visual stability of a page as it loads. It evaluates the amount of unexpected layout shift that occurs during the page loading process. CLS is expressed as a score between 0 and 1, where a lower score is better. A score of less than 0.1 is considered good.

Why CLS Matters

When a page is loading, users expect it to remain stable and usable, with no sudden or unexpected changes. However, layout shifts can occur due to a variety of factors, including the loading of slow-loading images or ads, content that is added or removed dynamically, and the use of web fonts.

Layout shifts can be frustrating for users and can lead to a poor user experience. A high CLS score indicates that a page is visually unstable, which can negatively impact user engagement, dwell time, and bounce rate.

How to Optimize CLS

Optimizing CLS requires taking several steps to ensure that the layout of the page remains stable and consistent as it loads. Here are some best practices for optimizing CLS:

  1. Define image and video dimensions: One of the most common causes of layout shifts is the use of images and videos without specifying their dimensions. Browsers need to know the dimensions of the images and videos in advance to reserve the necessary space for them. Defining the dimensions of images and videos can help prevent layout shifts.
  2. Reserve space for ads and iframes: Ads and iframes can be significant contributors to layout shifts. To prevent these elements from shifting the layout of the page, it’s best to reserve space for them in advance. This can be achieved by setting up the necessary space in the HTML or using placeholder elements.
  3. Avoid actions that trigger layout changes: Certain actions, such as changing the size of a font or changing the layout of an element, can trigger layout changes. Avoiding these actions can help prevent layout shifts.

Real-World Examples

Several websites have implemented CLS optimization techniques to improve their scores. One example is the website for the clothing brand Patagonia. By defining image dimensions and using placeholder elements for ads, Patagonia was able to reduce its CLS score from 0.32 to 0.01, resulting in a significant improvement in user experience.

Another example is the website for the food delivery service DoorDash. By optimizing images and reducing the number of third-party scripts, DoorDash was able to improve its CLS score from 0.24 to 0.05, resulting in a faster and more stable user experience.

By following these best practices and real-world examples, website owners and developers can optimize their CLS score and provide a better user experience.

Best Practices for Optimizing Core Web Vitals

In addition to optimizing the individual Core Web Vitals, there are some general best practices that can help improve overall website performance and user experience.

  1. Minimize Page Load Time One of the most important aspects of optimizing Core Web Vitals is reducing the overall page load time. This can be achieved by using techniques such as compressing images and other resources, minifying code, and leveraging browser caching. Implementing lazy loading for images and videos can also help reduce page load time by only loading content as it’s needed, rather than all at once.
  2. Reduce the Number of HTTP Requests The number of HTTP requests that a website generates can have a significant impact on its overall performance. Minimizing the number of requests by combining resources, reducing the number of third-party scripts, and avoiding unnecessary redirects can all help improve performance and reduce page load time.
  3. Implement a Content Delivery Network (CDN) A CDN is a network of servers that distribute website content to users based on their geographic location. By caching website content on multiple servers across different regions, a CDN can help reduce page load time and improve performance for users around the world.
  4. Regularly Monitor Core Web Vitals Optimizing Core Web Vitals is an ongoing process, and it’s important to regularly monitor and measure performance to identify areas for improvement. Tools like Google Lighthouse and PageSpeed Insights can provide valuable insights into website performance and suggest specific optimizations to improve Core Web Vitals.

By following these best practices and continually monitoring and optimizing Core Web Vitals, website owners can improve the user experience and help their websites rank better in search results.

In summary, optimizing Core Web Vitals is essential for providing a fast and smooth user experience on your website. Google’s recent algorithm update has placed even more emphasis on these metrics, making it more important than ever to prioritize them.

In this article, we’ve discussed the three main Core Web Vitals and provided best practices for optimizing each one. By focusing on reducing server response times, optimizing images and videos, leveraging browser caching, defining image and video dimensions, reserving space for ads and iframes, and avoiding actions that trigger layout changes, you can improve your website’s performance in terms of LCP, FID, and CLS.

Additionally, we’ve discussed other best practices, such as minimizing page load time, reducing the number of HTTP requests, and implementing a content delivery network (CDN), which can further improve your website’s overall performance.

Finally, we highly recommend monitoring Core Web Vitals regularly and using tools like Google Lighthouse and PageSpeed Insights to identify areas for improvement. By implementing these best practices and regularly monitoring your website’s performance, you can improve your Core Web Vitals and provide a better user experience for your visitors.

In conclusion, it’s time to start optimizing your Core Web Vitals and prioritize user experience on your website. By doing so, you can improve your search engine rankings, increase traffic, and ultimately, drive more conversions.


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