Landing page speed: how much it changes conversion

Everyone agrees a slow site is bad. Few people can say how much it costs. Without a number, speed ends up at the bottom of the list, behind “swap the hero photo” and “change the button copy.”

A case study published by Google's web.dev on June 24, 2026 puts a number on it. And it comes from a company every Brazilian founder knows: Nuvemshop, a platform with more than 180,000 stores.

What Nuvemshop changed and what it gained

The Nuvemshop team focused on one metric: LCP, the time until the largest element on screen appears. Comparing active Brazilian stores in January 2025 and January 2026, the results were:

• Pages with good LCP: from 57% to 96%. A 68% relative improvement.
• Pages passing Core Web Vitals: from 48% to 72%. A 50% relative improvement.
• Mobile conversion, from session to paid order: +8.9%. Measured on organic Google traffic.
• Mobile cart engagement: +8.4%.

The study doesn't include desktop numbers or the other two Core Web Vitals metrics. But if you sell on mobile, the message is clear.

The problem wasn't what they thought

The most useful part of the case is the team's admission: “Our initial hypothesis was image weight or server latency. We were wrong.”

The problem was the order. Carousels appear on 85% of Nuvemshop storefronts, and the carousel's first image is usually the largest element on screen. But the browser didn't know it was the priority. It waited in line like any other image.

The four technical changes

The team made four tweaks. All of them apply to an ordinary landing page:

1. Removed entrance animations from the first section. CSS transitions delayed the moment the browser recognized the main image.
2. Removed lazy loading from the first image. loading="lazy" is great for images further down. On the top image, it delays exactly what matters most. The change applied only to the first image of the first sections.
3. Marked the main image as high priority. With fetchpriority="high", plus validation to apply it only where the element could be the largest on screen. In the team's words: “if everything is high priority, nothing is.”
4. Expanded edge caching. Without serving stale prices or stock, while monitoring business metrics.

None of these changes required redesigning the store. The look stayed the same. What changed was the order in which the browser fetches each file, and that was enough to move conversion.

Speed as a business metric

The case also cites Deloitte research for Google, covering more than 30 million sessions across 37 brands: a 0.1-second speed gain can lift retail conversion by 8.4%. It's retail data, but it shows the link between speed and sales isn't unique to Nuvemshop.

The team closes with a line that applies to any product: “Fast storefronts aren’t just a technical achievement, they directly drive merchant success.” A fast page isn't just a technical win. It sells.

Speed checklist for your landing page

A landing page that converts starts fast, and founders' pages tend to have the same villains as a shop window: a big image at the top, entrance animations and third-party scripts. Before investing in anything else, check:

• Does the top image load first? It shouldn't have loading="lazy" and can get fetchpriority="high".
• Does the first section show without waiting on animation? Entrance effects up top delay what visitors see.
• Are images sized right for mobile? Serving the desktop image on mobile wastes data and time.
• How many third-party scripts load before the content? Chat, pixels and heatmaps add up.
• Do you measure with real-user data? PageSpeed Insights shows the LCP of people who visited your page, when there's traffic.
• Do you look at mobile first? That's where Nuvemshop saw the conversion gain.

How we do it at the Studio

Studio sites are designed for mobile from the first Figma sketch, and speed is a requirement, not a last-minute fix. Before publishing, we measure the page on mobile with Core Web Vitals, which also matter when your site doesn't show up on Google.

We use Claude Code and Figma for design and build. Tweaks like Nuvemshop's are small in code and big in results, and they fit any landing page. The price is fixed after discovery, with a deadline written into the contract.

If your landing page takes too long to show what matters, every second is costing you sign-ups. A fast site from the first version is part of what the Studio delivers in website and landing page design.