8 Best Practices for Managing Cumulative Layout Shift in WordPress

Cumulative Layout Shift (CLS) is a crucial metric in web performance, measuring a webpage’s visual stability. It quantifies unexpected layout shifts while a page loads, which can lead to a frustrating user experience as content moves around unexpectedly. A high Cumulative Layout Shift score indicates a poor user experience, where visitors might accidentally click on something they didn’t intend to because of sudden shifts.

This situation annoys users and can reduce a website’s trust and usability. Google recognizes the significance of Cumulative Layout Shift by incorporating it into its Core Web Vitals, directly affecting SEO rankings. Websites with better Cumulative Layout Shift scores rank higher in search results, making optimization essential for user satisfaction and search engine visibility.

1. Use a Quality Theme

Choosing a well-coded, CLS-optimized theme is essential for maintaining a stable and user-friendly website. A high-quality theme ensures elements on the page load predictably, reducing unexpected layout shifts that can frustrate visitors. Reputable theme providers offer options that prioritize performance and adhere to best coding practices.

For example, StudioPress’s Genesis Framework is widely praised for its clean code, fast load times, and minimal layout shifts. These factors make it an excellent choice for anyone looking to optimize their site’s cumulative layout shift. Selecting a theme from trusted sources enhances the user experience. It positively impacts SEO rankings by aligning with Google’s Core Web Vitals.

2. Optimize Images

Defining image dimensions is vital to prevent layout shifts. It ensures the browser allocates the correct amount of space for images before they load, avoiding sudden changes in the layout that can disrupt the user experience.

Proper image optimization prevents these shifts and improves website load speed, leading to faster page rendering and better performance. Setting width and height attributes in HTML, such as ‘<img src=”image.jpg” width=”600” height=”400”>’, helps maintain the intended layout.

Additionally, using CSS to define image sizes can further enhance stability. For example, Implementing responsive images with the ‘srcset’ attribute allows browsers to choose the most appropriate image size based on the user’s device and screen solution. This approach enhances visual stability and contributes to faster load times across different devices.

3. Preload Fonts

Font loading can significantly impact Cumulative Layout Shift. Browsers often load web fonts after the initial page load, causing text to re-render and shifting the layout unexpectedly. Preloading fonts reduces the timeframe for these layout shifts by ensuring fonts are loaded and ready to use when the content is rendered.

To preload fonts in WordPress, one can add a ‘<link rel=preload” href=” font.woff2” as=”font” type=”font/woff2” crossorigin=”anonymous”>’ to the website’s header. Users can do this by editing the theme’s ‘header.php’ file or using a custom function in the theme’s ‘functions.php’.

Tools and plugins like WP Rocket and Asset CleanUp Pro assist with font optimization, offering features that help preload fonts and improve overall site performance. These steps ensure a smoother visual experience, reducing layout shifts and enhancing user experience and SEO performance.

4. Minimize Third-Party Scripts

Third-party scripts can cause layout shifts by loading additional content — such as ads, widgets or social media feeds, after the main content has been rendered. These scripts can delay rendering, causing visible shifts that disrupt the user experience. Identifying and eliminating unnecessary third-party scripts is crucial for maintaining a stable layout. 

Website owners can start by auditing their scripts to determine which ones are essential and removing those that aren’t. Tools like Google Lighthouse, Chrome DevTools and WebPageTest can help monitor the impact of third-party scripts on Cumulative Layout Shift by providing detailed reports and insights. These tools allow the identification of problematic scripts, making optimizing the website for better performance and reduced layout shifts easier.

5. Implement Lazy Loading

Lazy loading images and iframes offers several benefits, primarily enhancing website performance and user experience by deferring the loading of non-critical resources until they are nearly in the user’s view.

This technique prevents unnecessary loading of off-screen content, reducing initial load times and conserving bandwidth. Enabling lazy loading in WordPress is straightforward. From WordPress version 5.5 onward, lazy loading is automatically applied to images using the ‘loading=”lazy”’ attribute. 

For more advanced control or to include iframes, users can use plugins like WP Rocket, Lazy Load by WP Rocket and a3 Lazy Load. These plugins provide user-friendly settings to quickly implement lazy loading across a site, ensuring faster load times and a smoother browsing experience.

6. Use WebP Images

The WebP format offers significant advantages for reducing image load times and Cumulative Layout Shift thanks to its superior compression capabilities. WebP lossless images are 26% smaller than PNGs and up to 34% smaller than comparable JPEG images. These numbers lead to faster loading times and reduced layout shifts due to delayed image rendering.

To convert and implement WebP images in WordPress, users can use plugins like Imagify, ShortPixel or EWWW Image Optimizer. These tools automatically convert existing images to WebP format and serve them to compatible browsers. These plugins handle the conversion process seamlessly, ensuring optimized images without manual intervention. They also help enhance overall site performance and user experience.

7. Define Ad Space

Dynamic ad loading can cause significant layout shifts as ads often load asynchronously, altering the layout once the initial content is rendered. This unpredictability can disrupt the user experience, leading to higher Cumulative Layout Shift scores. Setting fixed dimensions for ad slots is crucial in mitigating this issue. By reserving space for ads with specific width and height attributes, the browser can allocate the necessary space during the initial load, preventing sudden shifts.

Best practices for managing ads to minimize Cumulative Layout Shifts include using responsive ad units, implementing placeholders and lazy loading ads. Additionally, regularly monitoring ad performance and impact using tools like Google Publisher Console can help maintain a stable and user-friendly layout.

8. Avoid Flash of Unstyled Content

Flash of Unstyled Content (FOUC) occurs when a webpage briefly displays the browser’s default styles before fully loading the site’s CSS. This scenario leads to a noticeable flicker that can negatively affect user experience and contribute to Cumulative Layout Shifts.

This happens because the browser renders the page before the external CSS is fully loaded, causing layout shifts as the styles are applied. One effective technique to prevent FOUC in WordPress is to use critical CSS, which involves inlining the essential CSS — needed for the initial page load — directly into the HTML.

This ensures the most critical styles are applied immediately, minimizing layout shifts and improving visual stability. Plugins like WP Rocket or Autoptimize can help generate and implement critical CSS automatically. They reduce FOUC and optimize CSS delivery, ensuring a smoother and more stable user experience.

Start Implementing Best Practices

Incorporating these best practices will significantly enhance website performance, providing a smoother user experience and better SEO rankings. Maintaining a user-friendly and SEO-optimized WordPress site is essential for attracting and retaining visitors and ensuring the site performs well in search engine results.