HTTP Archive’s latest Core Web Vitals Technology Report ranks seven content management platforms and offers the surprising insight that page weight and PageSpeed Insights Lighthouse scores do not always predict Core Web Vitals performance.
Why Core Web Vitals Matter
Core Web Vitals (CWV) are metrics created by Google to show:
- How quickly a web page loads
- How stable it remains during loading
- And how responsive users may perceive the page.
While Core Web Vitals is a minor ranking factor, it is important because pages with high CWV scores perform faster and more smoothly for users and can benefit site owners with higher conversions and better ad performance. Sites with lower scores tend to present users with friction that can frustrate them, which in turn can increase abandonment rates and negatively impact conversions.
Does Page Weight Impact Core Web Vitals?
It is commonly understood that page weight affects Core Web Vitals scores. But page weight is not necessarily the dominant factor. So this comparison also examines median page weight to understand how closely it correlates with low or high CWV scores.
What emerges from the comparison suggests the relationship is not quite as straightforward as it seems.
How The Data Is Collected
The Core Web Vitals Technology Report combines public data from the Chrome UX Report (CrUX) and the HTTP Archive project. The data used for this comparison comes from global statistics, which can give a broader view of how websites perform across the widest range of devices and internet connections.
- CrUX collects anonymized real-world field performance data from Chrome users who opt into sharing usage statistics.
- HTTP Archive collects lab-based performance and technology data by crawling and testing websites across the web.
- The HTTP Archive median page weight dataset measures the typical transfer size of pages over time.
Comparing the two datasets (CrUX and HTTP Archive) makes it possible to examine whether page weight correlates with measured and real-world Core Web Vitals performance.
Duda Ranked Highest For Core Web Vitals
Duda ranked first in Core Web Vitals performance with approximately 85% of sites receiving a good CWV score. It also maintained one of the lightest median page weights in the comparison at roughly 1.78 MB.
The relationship between lighter pages and stronger CWV performance is immediately apparent. Duda paired relatively lightweight pages with the strongest CWV performance in the dataset.
#2 Ranked CWV Platform: Wix
Wix ranked second with roughly 80% of sites receiving a good CWV score.
Its median page weight measured approximately 2.55 MB, noticeably heavier than Duda but still lighter than several lower-performing platforms.
The data continues reinforcing the broader trend. Platforms carrying lower page weight generally clustered near the top of the CWV rankings.
#3 Ranked CWV Platform: Shopify
Shopify is ranked third for Core Web Vitals performance with roughly 79% of sites receiving a good CWV score. That’s a surprisingly strong ranking because shopping site performance tends to get dragged down by third-party scripts, customer tracking, and shopping-related features. Shopify sites also had the worst page weight scores and Lighthouse audit scores.
Page Weight Scores April 2026 (Lower Is Better)
- Astro: 1.65 MB
- Duda: 1.87 MB
- Drupal: 2.39 MB
- Joomla: 2.65 MB
- Wix: 2.67 MB
- WordPress: 2.76 MB
- Shopify: 3.77 MB
Lighthouse Audit Scores April 2026 (Higher Is Better)
- Astro: 68
- Wix: 62
- Duda: 54
- Drupal: 48
- Shopify: 47
- WordPress: 44
- Joomla: 43
Shopify sites had all these factors working against them and yet they still outperformed nearly all the other platforms in this comparison. What is going on?
The first takeaway is that reducing Page Weight is only one factor out of several for improving Core Web Vitals performance.
Another insight is that Lighthouse lab audit scores and real-world Core Web Vitals are not rewarding exactly the same things.
The Lighthouse audit is sensitive to:
- JavaScript payload
- Unused JS
- Render-blocking resources
- Synthetic throttling conditions
- Image inefficiencies
- Network waterfall structure
Why Shopify Sites May Score Highly For CWV
Sites hosted on Shopify may have high real-world Core Web Vitals performance because Shopify maintains stable rendering behavior, uses layouts coded to avoid shifting, delivers interactivity quickly, and aggressively optimizes resource delivery through CDN infrastructure and its hosting environment.
The above factors are the very things that respond well to real-world CrUX measurements:
- Measures actual user experience
- Includes caching effects
- Includes CDN behavior
- Includes repeat visits
- Reflects real devices and connection conditions
- Measures whether the page ultimately feels responsive and stable to users
Shopify’s results show that a site can have high page weight and low Lighthouse audit scores and still deliver a high-quality Core Web Vitals experience to users. Optimizing shopping websites is not easy. Shopify’s performance in this comparison is worth recognizing.
Why Does Astro Have Good Scores?
67% of sites using Astro received a good CWV score, placing it solidly in fourth place. Astro also maintained the lightest median page weight in the dataset. That combination of light page weight and solid Core Web Vitals performance reinforces the intuition that lightweight pages help with CWV scores. But Shopify’s example shows that page weight is not the only path toward better CWV performance.
Astro deserves a closer look, however, because the high CWV scores could be a reflection of the kinds of sites being deployed with it. For example, straightforward blog-style sites don’t need the kind of complex functionalities that drag down Core Web Vitals scores.
Astro performs well out of the box, but so does WordPress. A further review may show that the out-of-the-box Astro advantage may fade as website complexity increases.
Drupal Delivers Reliable CWV Performance
Drupal ranked fifth with roughly 64% of sites receiving a good CWV score.
Its median page weight measured approximately 2.28 MB, placing it near the middle of the comparison in both CWV performance and page weight size.
Drupal’s performance scores from January through April 2026 shows stability with no swings up or down. It began the year at 64% and ended April with the same 64% score. Stability is good, but an upward improvement, even a modest one, is arguably preferred.
What Is Undermining Joomla’s CWV Performance?
Joomla ranked sixth with approximately 58% of Joomla-based sites receiving a good CWV score.
The median page weight of sites using Joomla measured approximately 2.53 MB, which is better than some of the higher CWV ranked websites. This is another anomaly where a platform delivers low page weight but mediocre Core Web Vitals scores.
A review of HTTP Archive’s Lighthouse Audits performance shows that Joomla had the lowest Lighthouse scores of all the CMS platforms in this comparison.
Joomla Scores Lowest On Lighthouse Audits
- Astro: 68
- Wix: 62
- Duda: 54
- Drupal: 48
- Shopify: 47
- WordPress: 44
- Joomla: 43
Those low scores may indicate that execution factors, such as render-blocking resources, JavaScript behavior, image handling, and template or extension quality, may be the factors weighing down real-world CWV performance for Joomla-based sites.
WordPress Is Last Again
WordPress is ranked dead last in this comparison with approximately 49% of sites receiving a good CWV score. It ranked second to last in Lighthouse Audits just behind Joomla and was second to last for page weight with a median page weight of approximately 2.63 MB.
The contrast with Duda and Astro is especially sharp when comparing page weight:
- Websites created with Duda were 1.87 MB
- Websites created using Astro averaged 1.65 MB. .
- WordPress sites had a median page weight of approximately 2.63 MB.
The gap between the platforms is large enough that they no longer appear to be operating within the same performance range.
Median Page Weight And CWV Performance
The platforms with the lightest median page weights didn’t directly correlate with top Core Web Vitals performance.
Page Weight
- Astro: 1.57 MB
- Duda: 1.78 MB
- Drupal: 2.28 MB
Core Web Vitals Performance
- Duda: 85%
- Wix: 80%
- Shopify: 79%
Low Page Weight Does Not Guarantee Good CWV Performance
The data appears to support a relatively straightforward conclusion: lighter pages generally produce stronger Core Web Vitals performance. But Shopify shows that optimizing for page weight is not the sole path to better CWV performance. The answer lies in how efficiently platforms handle website complexity.
Shopify’s pages carry far more weight than competing platforms, largely because e-commerce sites require extensive JavaScript, product filtering systems, dynamic inventory functionality, images, personalization features, and interactive storefront elements.
Under a simplistic payload-size model, Shopify should perform considerably worse. But the platform continues producing CWV scores that outperform more lightweight platforms.
That suggests the conversation around performance should be as much about managing web page complexity as it is about minimizing page weight. The example of Shopify sites appears to point to web page complexity as the more important factor to optimize for.
- A lighter platform may still perform poorly if rendering and execution are handled inefficiently.
- A heavier platform may still perform well if its architecture aggressively optimizes how that complexity is delivered to users.
That’s the big takeaway from the comparison of different platforms.
Nevertheless, sites that are lightweight generally tended to demonstrate stronger CWV performance. But Shopify forces a more nuanced conclusion because it demonstrates that payload size alone does not determine outcomes.
The competitive advantage increasingly appears to belong to platforms capable of carrying complexity efficiently.
Takeaway
What Shopify’s results really show is that Core Web Vitals performance is not simply a contest to see which platform can ship the smallest pages. The more important question is what happens after real-world complexity enters the picture.
That’s where the individual CWV metrics become useful because they reveal the specific ways websites fail under pressure.
Largest Contentful Paint (LCP) often breaks when platforms load oversized images, delay discovery of the main image, block rendering with CSS and JavaScript, or force browsers to compete against too many high-priority resources at the same time. A site can have relatively small overall payloads and still perform poorly if the browser struggles to identify and render the most important visual content quickly.
Interaction to Next Paint (INP) exposes another weakness. Third-party scripts, tracking tags, hydration overhead, popups, sliders, chat widgets, and excessive JavaScript execution can all block the browser’s main thread and delay responsiveness. This is where website complexity becomes expensive because every additional feature competes for execution time.
Cumulative Layout Shift (CLS) often breaks when layouts are unstable. Images without reserved dimensions, late-loading ads, embedded media, injected interface elements, and dynamic content can all push visible content around while users are attempting to interact with the page.
This is where Shopify’s results become more interesting. Shopping sites naturally carry many of the exact elements that tend to damage LCP, INP, and CLS scores. Shopify also ranked only in the middle of the Lighthouse performance scores, which means its lab-test results were not especially strong compared with the rest of the platforms.
And yet Shopify still maintained one of the strongest real-world CWV performances in the comparison. When talking about CWV many SEOs focus on making sites faster. But if we’re going to take away something from this comparison, it’s that real-world CWV performance may come from how well a website handles the technical failure points and not focusing only on page weight type improvements.
Featured Image by Shutterstock/n_defender
