Core Web Vitals best practices

To achieve a website that delivers an exceptional user experience, it's crucial to follow best practices for optimizing Core Web Vitals. These metrics – Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS) – are central to ensuring that your site performs well, retains users, and meets Google's SEO standards. Here's how to optimize each metric effectively.

Improving Largest Contentful Paint (LCP)

Definition: LCP measures how long it takes for the largest content element on a page to load and become visible to the user. This element is often an image, video, or block of text.

Ideal Performance Benchmark: LCP should be 2.5 seconds or less.

Best Practices:

1. Optimize Server Response Times:

   • How: Use faster hosting solutions, implement server-side caching, and optimize server configuration.
   • Benefit: Reducing server response times ensures that the first byte is received quickly, helping decrease LCP.

2. Efficient Resource Loading:

   • How: Prioritize loading critical resources and defer non-essential CSS and JavaScript.
   • Benefit: This ensures that the largest content element loads without unnecessary delays.

3. Compress and Properly Size Images:

   • How: Use image compression tools and serve next-gen formats like WebP.
   • Benefit: Smaller image sizes load faster, improving LCP.

4. Utilize a Content Delivery Network (CDN):

   • How: Use a CDN to deliver content from servers closer to the user's geographic location.
   • Benefit: CDNs distribute load and reduce the time it takes for content to reach users, enhancing LCP.

Enhancing Interaction to Next Paint (INP)

Definition: INP measures the responsiveness of a page during user interactions, such as clicking buttons or entering data in forms.

Ideal Performance Benchmark: An INP of 200 milliseconds or less is considered optimal.

Best Practices:

1. Minimize and Defer Non-Critical JavaScript:

   • How: Identify and minimize heavy JavaScript files using code-splitting techniques and defer non-critical scripts.
   • Benefit: Reducing JavaScript execution helps pages respond faster to user input.

2. Break Up Long Tasks:

   • How: Divide large tasks into smaller chunks using requestAnimationFrame or setTimeout to prevent main-thread blocking.
   • Benefit: Smaller tasks allow the browser to process user inputs promptly, enhancing INP.

3. Optimize Third-Party Scripts:

   • How: Assess third-party scripts to determine their necessity and use asynchronous loading where possible.
   • Benefit: Reduces delays caused by external scripts, ensuring smoother user interactions.

Reducing Cumulative Layout Shift (CLS)

Definition: CLS measures the visual stability of a page and identifies unexpected layout shifts that occur during loading.

Ideal Performance Benchmark: A CLS score of less than 0.1 is considered good.

Best Practices:

1. Specify Size Attributes for Images and Videos:

   • How: Add width and height attributes or use CSS to specify the dimensions of media.
   • Benefit: Predefined space prevents layout shifts when media is loaded, reducing CLS.

2. Reserve Space for Dynamic Content:

   • How: Use CSS to allocate space for elements that load asynchronously, such as ads or embeds.
   • Benefit: Ensures that content doesn't push other elements unexpectedly, maintaining layout stability.

3. Avoid Inserting New Content Above Existing Content:

   • How: Implement practices that keep new content, such as banners or notifications, from appearing above content already loaded.
   • Benefit: Prevents layout jumps that disrupt user interaction and contribute to a poor CLS score.

Example: An eCommerce site can improve CLS by defining image sizes and reserving space for promotional banners. This avoids sudden layout shifts that can lead to user frustration and lost sales.

Optimizing Core Web Vitals is essential for delivering a positive user experience, improving search engine rankings, and boosting conversions. By focusing on best practices for LCP, INP, and CLS, websites can meet performance benchmarks that keep users engaged and encourage long-term success. Start implementing these optimizations to ensure your site not only meets but exceeds user expectations.