In a previous post, we talked about the real-world PageSpeed reality for typical websites. Now it’s time to move past opinion and look at real companies, real experiments, and measurable business impact.
I’ve selected four real, well-documented cases where performance and Core Web Vitals improvements produced concrete results, followed by two broader data points that help put everything into perspective — no hype, no miracle promises.
Four cases with real impact
These are not small or isolated cases. They involve large companies, operating in highly competitive markets, spending millions to improve and optimize their code quality.
Vodafone: +8% in sales after improving LCP
Vodafone ran a controlled A/B test comparing two versions of a landing page. The main difference between them was performance, especially Largest Contentful Paint (LCP). After improving LCP by roughly 31%, the results were:
- +8% increase in sales
- +15% increase in lead-to-visit rate
- +11% increase in cart-to-visit rate
This is one of the clearest examples of how performance directly impacts conversion when there is traffic volume and a well-defined funnel.
Google Search: a direct correlation between speed and abandonment
Google itself has published data showing that:
- When load time increases from 1s to 3s, the probability of bounce increases by 32%
- When it goes from 1s to 5s, bounce probability can increase by up to 90%
This is not a ranking case. It’s more important than that: a real user behavior signal that directly affects retention, engagement, and conversion metrics.
T-Mobile: aligning performance metrics with business metrics
T-Mobile implemented monitoring based on real user data (field data) using web-vitals.js. They found that degradations in metrics such as LCP and CLS were directly associated with:
- higher bounce rates
- lower conversion rates
- worse perceived user experience
This case is not about a single headline number. It’s about proving that performance degradations show up directly in business metrics.
Shopify: where every 100ms matters
Shopify published internal data showing that:
- 100ms improvements in load time resulted in measurable increases in conversion rate
- Small performance regressions caused negative revenue impact at scale
This type of impact only shows up when traffic operates at massive scale.
Data that puts everything into context
Not every performance improvement shows up as direct conversion. These data points help explain the real role of Core Web Vitals within the ranking ecosystem.
Google: Core Web Vitals are a ranking factor, but not a dominant one
Google officially states that Core Web Vitals are part of the ranking signals, but they do not replace relevant content, authority, or satisfied search intent. According to John Mueller (Google Search Relations), CWV works more as a tie-breaker than as a primary ranking factor.
Studies show many top-ranking sites don’t pass all CWV thresholds
Independent analyses indicate that many well-ranking pages do not meet all Core Web Vitals thresholds, reinforcing that:
CWV helps, especially in competitive scenarios, but it does not replace content, authority, or well-served intent.
So… what does this prove?
- Performance and Core Web Vitals generate real impact when there is a technical bottleneck, meaningful traffic volume, and conversion on the table
- They are part of modern SEO, but they don’t replace content, authority, or intent
- Improving CWV helps you compete better, not “hack” rankings
Performance is a leverage point — powerful, but contextual. When there is scale and a real bottleneck, it turns into revenue. Outside of that, it turns into cost. Mature architecture is not about chasing perfect scores — it’s about knowing when to stop optimizing and start delivering value.
Before optimizing another 5 points of CWV, validate whether it actually solves a real business problem.