6 min read

Fast Pages Win Customers (Core Web Vitals) - 2025 Edition

Your website speed shapes both UX and organic performance. A few hundred milliseconds can swing bounce rates, conversions, and revenue. Below is a data-driven, skimmable version of our Core Web Vitals guide - built to read like a stats article with clear actions you can ship today.
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By: LumioForge Team
Updated: September 7, 2025 - Europe/Zagreb

Table of Contents

• Website Speed Statistics

• Mobile Website Speed Statistics

• Core Web Vitals at a Glance - LCP, INP, CLS

• Real-User Data - CrUX vs Lab - Lighthouse

• Image - CDN - Cache Checklist

• Before - After Speed Snapshot - template

• Tools and References

Website Speed Statistics

• As page load increases from 1s to 3s, the probability of bounce rises about 32 percent - see the Think with Google snapshot of page load statistics (link).

• As mobile load increases from 1s to 10s, bounce probability can jump around 123 percent - Google’s mobile speed benchmarks explain the relationship between load time and bounce (link).

• A 0.1s improvement on mobile has been linked to notable conversion lifts - see Deloitte’s study, Milliseconds Make Millions (summary and the original PDF on Think with Google, where retail rose by about 8.4 percent and travel by about 10.1 percent, depending on context link).

• Google’s page experience guidance clarifies how Core Web Vitals factor into Search when content quality is comparable - focus on overall helpfulness plus good CWV (link).

• Content Delivery Networks reduce latency by caching content closer to users - see Cloudflare’s learning center overview of CDNs (link).

Mobile Website Speed Statistics

• 53 percent of mobile visits are abandoned if a page takes more than 3 seconds to load - see the Think with Google mobile site load time statistics (link) and supporting benchmark PDF (link).

• As 1s grows to 10s on mobile, bounce probability increases 123 percent - see the benchmark article (link).

• Small improvements matter - a 0.1s lift correlated with better funnel progression and conversions in the Deloitte - Google study (web.dev case study).

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Core Web Vitals in 60 seconds

• LCP - Largest Contentful Paint
  What it tells you: how quickly the main, above-the-fold content appears.
  Target: 2.5s or faster at the 75th percentile. Learn LCP basics on web.dev (link) and Lighthouse docs (link).

• INP - Interaction to Next Paint
  What it tells you: end-to-end responsiveness to taps, clicks, and typing.
  Target: 200 ms or faster at the 75th percentile. INP replaced FID in March 2024 - details on web.dev and Google Search Central (web.dev announcement, overview article, Search Central post).

• CLS - Cumulative Layout Shift
  What it tells you: visual stability during load and interaction.
  Target: 0.1 or less at the 75th percentile. Guides on web.dev and MDN explain how to prevent shifts (web.dev, optimize CLS, MDN glossary).

Why p75 matters - thresholds for good, needs improvement, poor are evaluated at the 75th percentile across real users - see web.dev’s threshold explainer (link).

Real-User Data vs Lab Tests

• Field data - CrUX and the field section in PageSpeed Insights
  Field data represents anonymized real-user experience - see PSI’s about page (link) and the CrUX docs (overview, API).

• Lab data - Lighthouse and the lab section in PageSpeed Insights
  Use lab data to diagnose issues before shipping. Open PSI (tool) and read the dev docs (about PSI).

Tip: in PSI, scan the Origin Summary for pass rates, then use Diagnostics to surface heavy images, render-blocking resources, long main-thread tasks, and layout shifts. For ongoing monitoring, check the Core Web Vitals report in Search Console (how it works, Search Console about).

Image - CDN - Cache Checklist

Images

• Export at exact display dimensions and prefer AVIF or WebP where supported.

• Add loading="lazy" to noncritical images - see MDN’s guide and web.dev’s browser-level lazy loading (MDN, web.dev).

• Reserve explicit width and height to prevent layout shifts - see CLS optimization guide (link).

Delivery

• Serve static assets through a reputable CDN to cut round trips - Cloudflare’s overview is a solid primer (link).

• Enable text compression for HTML, CSS, and JS - see web.dev and Chrome docs on gzip and Brotli (optimize encoding, Lighthouse - enable compression).

Caching

• Version static files and set long-lived cache headers for CSS, JS, and images - start with web.dev’s HTTP cache guide and MDN’s Cache-Control reference (web.dev, MDN Cache-Control).

• Avoid caching personalized HTML. Use CDN or server rules to differentiate static vs dynamic routes.

Code and third parties

• Defer or remove nonessential scripts. Load embeds on interaction where possible.

• Keep the DOM light and break up long tasks to improve INP - see common LCP and INP pitfalls on web.dev (LCP misconceptions, INP article).

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Before - After Speed Snapshot - template

Use this format in stakeholder updates. It ties Core Web Vitals to business metrics without over-promising causality.

How to justify the work

• Reference established research showing that faster mobile experiences correlate with higher conversion and lower abandonment - see Think with Google’s speed stats and the Deloitte study (1s to 3s = +32 percent bounce, 1s to 10s = +123 percent bounce, Milliseconds Make Millions).

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What to improve first

1. Optimize LCP

• Compress and properly size the hero media, inline critical CSS, reduce server TTFB, and preconnect to key origins - start with the LCP article on web.dev (link).

2. Improve INP

• Identify long main-thread tasks, split bundles, avoid heavy hydration, and prefer interaction-triggered loading - see the INP overview (link).

3. Stabilize CLS

• Set explicit sizes for images and embeds, reserve ad slots, and avoid inserting content above existing content - see CLS optimization (link).

4. Harden delivery

• CDN at the edge, text compression, and long-term caching for versioned static assets - see Cloudflare CDN overview and HTTP cache guide (CDN, HTTP cache).

5. Re-test and monitor

• Validate in PageSpeed Insights for both field and lab data and track Core Web Vitals in Search Console (PSI, Search Console CWV report).

Tools and References

• Page experience guidance - Google Search Central (link).

• Core Web Vitals overview - Google Search Central (link).

• LCP - web.dev (link).

• INP - web.dev announcement and guide (announcement, guide).

• CLS - web.dev and MDN (web.dev, MDN).

• Mobile speed and bounce stats - Think with Google (1s to 3s = +32 percent, 1s to 10s = +123 percent, 53 percent abandon >3s).

• Milliseconds Make Millions - Deloitte and Think with Google (summary, PDF).

• Lazy loading - MDN and web.dev (MDN, web.dev).

• HTTP caching - web.dev and MDN (web.dev, MDN Cache-Control).

• CDN basics - Cloudflare Learning Center (link).

Speed is one of the rare improvements that helps every visitor and every channel. Keep images lean, deliver at the edge, cache aggressively, trim scripts, and validate with real-user data. When you are ready to ship a roofing site that feels instant and earns more booked estimates - claim your spot.