A Complete Recipe for Solving Bad User CLS En Masse
Website performance directly impacts user experience and search engine rankings. Core Web Vitals (CWV) like Cumulative Layout Shift (CLS) are crucial metrics reflecting this. A high CLS score indicates a poor user experience, signifying unexpected page layout changes that frustrate visitors. This article provides a comprehensive recipe for tackling high CLS scores across your website, effectively improving user experience and boosting SEO.
Understanding the Problem: Why High CLS?
Before diving into solutions, it's vital to understand why your website suffers from bad CLS. Common culprits include:
- Unoptimized Images: Images without specified dimensions cause layout shifts as the browser renders them.
- Advertisements: Improperly implemented ads can unexpectedly change the layout.
- Embedded Content: Third-party embeds like videos or social media feeds may shift elements as they load.
- Fonts: Slow-loading fonts can disrupt layout stability.
- Dynamically-Sized Content: Content whose size isn't known until after loading can lead to shifts.
The Recipe: Ingredients for Low CLS
Here's a multi-step approach to reducing your website's CLS, addressing the root causes effectively:
1. Specify Image Dimensions: The Foundation
- Use
<img>
tags withwidth
andheight
attributes: Always provide explicit dimensions for every image. This prevents layout shifts as the browser knows the image's size beforehand. - Use responsive images: Implement responsive techniques like
srcset
to serve appropriately sized images based on the user's device. This combines the precision of specified dimensions with optimization for different screen sizes.
2. Tame the Ads: Controlling External Influences
- Use a responsible ad network: Choose a reputable ad network that prioritizes user experience and adheres to best practices.
- Reserve ad space: Allocate specific space for ads within your layout. This ensures that the ads don't unexpectedly push other elements around.
- Place ads strategically: Avoid placing ads above the fold, especially near crucial interactive elements.
3. Manage Embeds: Integrating External Resources Carefully
- Use placeholders: Show a placeholder or loading indicator while embedded content is loading. This prevents the layout from jumping as the embed loads.
- Size embeds appropriately: Ensure you set dimensions for embedded content to avoid layout shifts.
4. Optimize Fonts: Ensuring Fast Loading
- Use web fonts efficiently: Load only the necessary fonts and utilize techniques like font subsetting to minimize download size.
- Preload critical fonts: Prioritize loading critical fonts above the fold to improve initial page load stability.
5. Control Dynamic Content: Preventing Unpredictable Sizes
- Use CSS for layout: Whenever possible, avoid relying solely on JavaScript to control the layout. JavaScript's asynchronous nature can lead to layout instability.
- Reserve space for dynamic content: Allocate placeholder space for dynamic content, ensuring that its loading doesn't disrupt the existing layout.
Monitoring and Iteration: The Continuous Improvement Process
Reducing CLS is an iterative process. After implementing these steps, regularly monitor your CLS score using tools like Google PageSpeed Insights. This will allow you to identify areas for continued improvement.
By carefully following this recipe and continuously monitoring your progress, you can effectively reduce your website's CLS score, resulting in a better user experience and improved SEO rankings. Remember that a smooth, consistent user experience is paramount for engagement and conversion.