How to Achieve a CLS Score Below 0.1

Cumulative Layout Shift (CLS) is one of the most frustrating web performance issues for both users and developers. If you’ve ever clicked the wrong button because a page element suddenly shifted—yep, that’s CLS in action. 

For your WordPress website to offer a smooth and stable user experience, your CLS score needs to be below 0.1—and the good news? It’s totally achievable.

In this guide, we’ll show you how to fix CLS issues and maintain a stable layout.

What Is CLS and Why Does It Matter?

Cumulative Layout Shift (CLS) is a metric that evaluates how much your web page layout unexpectedly shifts while it loads. It’s a critical component of Google’s Core Web Vitals, which directly affects your SEO rankings, bounce rates, and conversion rates.

These shifts happen when elements—like fonts, images, ads, or buttons—load asynchronously and suddenly push other content around. This causes frustration for users who may click the wrong thing, miss information, or leave the site altogether.

Ideal CLS Score:

Score Range	Status	Impact
Less than 0.1	Good	No noticeable layout shifts, great user experience
0.1 – 0.25	Needs Improvement	Some visible layout shifts can annoy or confuse users
More than 0.25	Poor	Frequent shifts hurt engagement and search visibility

Why CLS is a Core Web Vitals

CLS is not just about aesthetics. It’s a performance signal Google uses to evaluate how usable your website is. High CLS scores:

• Damage your search rankings
  
• Increase bounce rates
  
• Lower conversion rates
  
• Lead to poor engagement metrics (especially on mobile)
  

From an SEO standpoint, even if your content is great, a janky, shifting interface can lead Google to rank you lower than more stable competitors.

Google’s verdict: If your CLS score is above 0.1, you’re already at a disadvantage.

How to Check the Current CLS Score of Your Site

Before you start optimizing, it’s essential to measure your current CLS score to know where you stand—and track your improvements along the way. Here are the top methods to check your site’s CLS score:

1. Google PageSpeed Insights

This is the most popular and beginner-friendly tool.

• Visit: PageSpeed Insights
  
• Enter your URL and click “Analyze.”
  
• Scroll down to the “Diagnostics” and “Core Web Vitals” sections
  
• Look for Cumulative Layout Shift (CLS)
  

It shows both real-world (field) and lab data.

2. Chrome DevTools (Lighthouse)

For real-time testing during development.

• Open your website in Google Chrome
  
• Right-click > Inspect > go to the Lighthouse tab
  
• Choose Mobile or Desktop, then click “Generate report.”
  
• Your CLS score will appear in the Performance section
  

Great for testing sandbox sites from InstaWP before pushing changes live.

3. Google Search Console

For site-wide insights over time.

• Go to Search Console > Core Web Vitals
  
• View performance data for both mobile and desktop
  
• CLS issues will be highlighted in the report
  

Best for tracking ongoing performance across all pages.

4. Web Vitals Chrome Extension

For quick, live metrics on any page.

• Install Web Vitals Extension
  
• Visit any page, and the extension will display real-time CLS, LCP, and FID values
  

Perfect for quick spot-checks as you optimize.

Tip for Agencies:

When testing client sites, use InstaWP to clone the environment and run all CLS checks in staging before touching the live site. This ensures a safe workflow and prevents live performance dips.

How to Achieve a CLS Score Below 0.1

Now that you have a solid understanding of what CLS is and why it matters, the next step is learning how to bring your CLS score below the golden threshold of 0.1—and keep it there.

To do this effectively, we’ll use two essential tools:

• InstaWP for setting up a safe and instant staging environment to test your fixes without touching your live site.
  
• Autoptimize to implement performance improvements that directly reduce layout shifts.
  

Together, these tools offer a powerful, low-risk way to fine-tune your website’s frontend behavior and achieve a seamless, stable user experience.

Let’s walk through each step in detail.

Step 1: Start with a Testing Ground Using InstaWP

Before applying fixes to your live site, create a staging environment of your live site. Get the CLS score using the above-mentioned methods. 

Step 2: Install and Configure Autoptimize for Layout Stability

Autoptimize is a lightweight plugin that optimizes scripts, styles, and fonts—major culprits behind CLS. Install and activate it on your staging site. 

Next, you have to configure the plugin the right way to improve the CLS. Your recommended settings are: 

Optimize CSS Code: Combine and inline critical CSS.
Load CSS Asynchronously: Prevent render-blocking styles.
Aggregate JavaScript Files: Helps prevent JS from delaying page paint.
Lazy-load Images: Delays image load until needed.
Preload Fonts: Prevent font swap issues.

How to Configure:

1. Install and activate Autoptimize.
   
2. Navigate to Settings > Autoptimize.
   
3. Enable:
   
   • “Optimize CSS Code”
     
   • “Aggregate CSS-files”
     
   • “Inline and Defer CSS”
     
   • Enable lazy-load.
     
   • Preload key fonts (add font URLs manually).
     

Pro Tip:

Use tools like WebPageTest or PageSpeed Insights to identify fonts and scripts causing layout shifts.

Step 3: Reserve Space for Dynamic Elements

Many CLS issues stem from:

• Images without dimensions
  
• Ads/widgets loading dynamically
  
• Fonts swapping after page render
  

Fixes:

• Always define width and height for images.
  
• Use CSS to set fixed heights for ad slots or embed containers.
  
• Use font-display: swap with preloaded fonts to reduce reflow.
  

Example:

<img src=”hero.jpg” width=”1200″ height=”600″ alt=”Hero Banner” />

This prevents the image from shifting content after it loads.

Step 4: Use Critical CSS and Reduce Render-Blocking Resources

Autoptimize integrates with Critical CSS generation tools (like criticalcss.com) to extract only the styles needed for above-the-fold content.

You can also:

• Remove unused CSS using PurgeCSS or Asset CleanUp.
  
• Defer non-essential JavaScript using Async JS or through Autoptimize’s settings.
  

Step 5: Test and Validate with InstaWP

With changes made in your InstaWP sandbox:

1. Visit your site using Lighthouse in Chrome DevTools.
   
2. Check the Performance tab and view your new CLS score.
   
3. Aim for a value under 0.1 consistently across desktop and mobile.
   

Once stable, replicate the settings to your live site or deploy directly from InstaWP if you’re using its managed WordPress hosting. 

Final Checklist: Quick Fixes for Reducing CLS

Issue	Solution
Image shifts	Add width/height attributes
Ad/content jumps	Pre-allocate space using CSS
Font swap delay	Preload fonts and use font-display: swap
Layout shift on scroll	Avoid inserting elements dynamically above the fold
Third-party script layout lag	Load non-critical JS asynchronously
Slow initial paint	Inline critical CSS with Autoptimize

Why InstaWP + Autoptimize = Perfect Combo for Developers

InstaWP lets you test performance fixes in isolated environments. No risk. No downtime.
Autoptimize makes frontend performance optimization simple—perfect for devs who want results, fast.

Together, they help you:

• Achieve sub-0.1 CLS scores
  
• Maintain SEO health
  
• Delight users with visually stable pages
  

Final Thoughts

CLS is a silent killer of user experience—but it’s fixable. With tools like Autoptimize to streamline your frontend and InstaWP to safely test changes, you have everything you need to crush the sub-0.1 CLS target.

Ready to see your CLS score drop?
Launch a free sandbox with InstaWP and get optimizing today.

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