CLS (Cumulative Layout Shift)

CLS is a metric that measures the visual stability of a webpage, quantifying how much content shifts unexpectedly during loading.

More About Cumulative Layout Shift (CLS)

Importance in User Experience: High CLS can lead to a poor user experience, as content moving around can be disorienting.

Calculation: Based on the impact fraction and distance fraction of unstable elements.

Optimization: Involves sizing images and embeds, and avoiding inserting new content above existing content.

Role in Core Web Vitals: One of Google’s Core Web Vitals, important for SEO and user experience.

In WordPress, CLS issues can occur due to various factors, such as late-loading images, ads, fonts, or dynamic content. These issues can lead to a poor user experience, especially on slower connections or less powerful devices.

How to Improve CLS in WordPress for Better Website Performance

1. Optimize Images:
   • Properly size and compress images to ensure they don’t push content down as they load. Use responsive image techniques to specify different image sizes for various screen resolutions and viewports.
2. Preload Fonts:
   • Preload web fonts in your WordPress theme to prevent text from shifting when fonts are fetched from external sources.
3. Eliminate Third-Party Scripts:
   • Reduce reliance on third-party scripts, such as ads and social media widgets, as they can contribute to CLS issues. Consider using asynchronous loading or lazy loading for such resources to minimize their impact on page layout.
4. Specify Image Dimensions:
   • Always include the width and height attributes in your image tags. This informs the browser about the image’s dimensions, allowing it to allocate space correctly.
5. Use CSS Grid or Flexbox:
   • Utilize modern CSS layout techniques like CSS Grid or Flexbox to create stable and responsive layouts that are less prone to layout shifts.
6. Lazy Load Images and Videos:
   • Implement lazy loading for images and videos, so they load only when they enter the viewport. This reduces the chances of content shifting while the page loads.
7. Avoid Dynamic Content Above the Fold:
   • Be cautious when placing dynamic content, such as ads or videos, at the top of your pages. If this content loads asynchronously, it can cause significant layout shifts. Consider reserving space for such content to maintain layout stability.
8. Test and Monitor:
   • Regularly test your WordPress website using tools like Google PageSpeed Insights, Lighthouse, or web.dev to identify and address CLS issues. Continuously monitor your site’s performance to catch and resolve unexpected shifts.
9. Update Plugins and Themes:
   • Keep your WordPress plugins and themes up to date, as updates may include optimizations and fixes for CLS-related issues.
10. Consider a Performance Plugin:
    • Consider using a performance optimization plugin for WordPress that includes CLS improvements as part of its feature set. These plugins often automate many of the best practices mentioned above.

Improving CLS in WordPress is essential not only for SEO but also for delivering a positive user experience. Visitors are more likely to engage with and stay on websites that load smoothly and don’t exhibit disruptive layout shifts.