Core Web Vitals Performance – CMS Comparison

Core Web Vitals (CWV) have become the gold standard for measuring real-world user experience on the web. As Google continues to focus on performance as a ranking factor, understanding how different Content Management Systems (CMS) perform has never been more critical.

In this post, we dive deep into the performance metrics of six leading CMS platforms: WordPress, Wix, Squarespace, Joomla, Duda, and Drupal, using real-world data collected from the HTTP Archive and the Chrome User Experience Report (CrUX).

What Are Core Web Vitals?

Core Web Vitals are a set of standardized metrics developed by Google to quantify user experience. These metrics focus on three key areas:

1. Largest Contentful Paint (LCP) – Loading performance (Target: <2.5s)

2. Cumulative Layout Shift (CLS) – Visual stability (Target: <0.1)

3. Interaction to Next Paint (INP) – Responsiveness (Target: <200ms)

As of  March 2025, INP officially replaced First Input Delay (FID), marking a significant shift in how responsiveness is measured. INP provides a fuller picture by evaluating all user interactions, not just the first one.

Data Sources and Methodology

The performance comparison is based on mobile data and leverages two key data sets:

• Chrome User Experience Report (CrUX): Real-world data from opted-in Chrome users.

• HTTP Archive: Lab-based performance tests run on real pages, typically homepages.

📌 Important Notes:

• Scores are represented as percentages, indicating the proportion of visits with a “Good” Core Web Vitals score.

• Each CMS was evaluated based on a standardized set of metrics for consistency.

Top Performing CMS Platforms 

🥇 1. Duda – 71% of sites passed Core Web Vitals

Duda, a closed-source platform primarily used by agencies, tops the chart with a staggering 71% of its websites achieving a good CWV score.

Why Duda performs well:

• Built-in performance optimizations (lazy loading, minification).

• Server-side rendering and CDN integration.

• Less dependency on third-party plugins.

Real-World Example: A portfolio site built with Duda showed an LCP of 1.7s and INP of 180ms, well within the “Good” thresholds.

🥈 2. Squarespace – 58%

Squarespace surprised many by increasing its score in 2025 by +3.92 percentage points, making it the only CMS in this study to improve performance.

Performance Boost Factors:

• Consistent, optimized themes.

• Recent platform upgrades targeting responsiveness.

• Minimal plugin ecosystem = fewer render-blocking resources.

🥉 3. Drupal – 54%

Drupal maintains a solid mid-tier position. As an open-source CMS geared toward developers, Drupal’s performance often reflects the skill of its implementers.

What helps Drupal:

• Extensive caching strategies.

• Granular control over assets and templates.

However, it still dropped 2.58 percentage points compared to the beginning of the year, possibly due to heavier image usage and custom scripts.

4. Wix – 52%

Wix sites have historically struggled with speed due to their JavaScript-heavy architecture. In April 2025, Wix dropped 7.11 percentage points—the largest decline among all platforms.

What’s going wrong?

• Heavy reliance on dynamic JS content.

• Third-party widgets and animations bloating INP scores.

Wix is actively rolling out performance updates, but developers using it should pay close attention to image sizes and scripting.

5. Joomla – 43%

Joomla, once a dominant player in the CMS space, is seeing a moderate decline. It lost 2.84 percentage points since January.

Challenges:

• Limited core performance enhancements.

• Outdated extensions and themes may not be INP-friendly.

6. WordPress – 38%

Despite being ranked last, WordPress is arguably the most resilient CMS in this list. Its performance only dropped by 0.71 percentage points, a significantly smaller dip compared to others.

Fun Fact: WordPress powers 43.2% of all websites on the internet.

📈 WordPress 6.5 (April 2025) – A Turning Point

WordPress 6.5 introduced over 100 performance improvements, including:

• Deferred loading for stylesheets.

• Better support for lazy loading.

• Reduced TTFB (Time to First Byte).

However…

• The average Page Weight increased from 568.48 KB to 579.92 KB.

• Image payloads alone grew by 49.5 KB—likely due to user-uploaded content, not WordPress core.

Live Example: A news blog using Astra + WP Rocket had a good INP (190ms) and CLS (0.03), but failed LCP (3.1s) due to large hero images.

Performance Drop Analysis (Jan–Apr 2025)

CMS	Performance Change (%)
Squarespace	+3.92
WordPress	-0.71
Drupal	-2.58
Joomla	-2.84
Duda	-5.41
Wix	-7.11

The standout takeaway: Only Squarespace improved during this period, while every other CMS saw a performance dip—mostly due to the INP update and page weight increases.

Why Did Performance Drop in 2025?

✅ Introduction of INP (Interaction to Next Paint)

INP replaced FID as an official Core Web Vital in March 2025. Unlike FID, which only measured first input delay, INP measures the slowest interaction in a user’s entire visit.

This change has disproportionately affected CMS platforms that rely on:

• Heavy JavaScript frameworks

• Dynamic content loading

• User interface widgets (e.g., live chats, sliders)

Best Practices to Improve CWV (Regardless of CMS)

1. Optimize Images: Use modern formats like WebP or AVIF.

2. Minimize JavaScript: Defer non-critical scripts.

3. Use a CDN: Reduce TTFB and latency.

4. Limit Plugins: Only use well-maintained, performance-oriented add-ons.

5. Preload Fonts & Critical CSS: Reduce LCP and render time.

FAQs

What is a “Good” Core Web Vitals score?

A “Good” score means the website passes all three metrics:

• LCP < 2.5s

• INP < 200ms

• CLS < 0.1

Why did WordPress perform poorly despite updates?

While WordPress core improved, the performance depends heavily on how users build their sites—theme choice, plugins, and media optimization matter a lot.

Is Duda really better than WordPress?

In raw CWV performance—yes. But Duda is closed-source and limited in flexibility. WordPress wins in ecosystem and customization.

❓ How can I test my site’s Core Web Vitals?

Use PageSpeed Insights or Web Vitals Chrome Extension.

Conclusion

If your priority is speed and performance out of the box, Duda leads by a wide margin. However, if you’re looking for flexibility and control, WordPress remains a strong contender—just be mindful of how you build and maintain your site.

Every platform in this comparison has made measurable improvements and offers different trade-offs. The key to success lies not just in picking the fastest CMS, but in how effectively you optimize your content, media, and scripts.