Sergiu Marcu
SEO June 16, 2026 7 min read

Core Web Vitals in 2026: Why Your Site's Speed Affects Sales

Core Web Vitals in 2026: Why Your Site's Speed Affects Sales

If you run a website for your business and haven't heard of Core Web Vitals, you're probably losing money without realizing it. That's not an exaggeration - it's a fact documented by Google and confirmed by thousands of site tests.

Core Web Vitals are a set of metrics Google uses to evaluate the user experience on your site. Since 2021, these metrics have directly influenced your ranking in search results. And in 2026, their importance has only grown.

What are Core Web Vitals?

Google has defined three core metrics that measure the quality of a site's experience:

LCP - Largest Contentful Paint

LCP measures how long it takes for the largest visible element on the page to finish loading. That could be a hero image, a large headline, or a block of text.

Thresholds:

  • Good: under 2.5 seconds
  • Needs improvement: 2.5 - 4 seconds
  • Poor: over 4 seconds

A poor LCP means visitors are staring at a blank or incomplete page for several seconds. According to Google's research, the probability of a visitor leaving increases by 32% when load time goes from 1 to 3 seconds.

INP - Interaction to Next Paint

INP replaced FID (First Input Delay) in 2024 and measures how quickly a site responds to user interactions. A click on a button, a tap on a link, a scroll - every action needs a fast visual response.

Thresholds:

  • Good: under 200 milliseconds
  • Needs improvement: 200 - 500 milliseconds
  • Poor: over 500 milliseconds

A poor INP makes a site feel "stuck" or "frozen." Users click multiple times, get frustrated, and leave.

CLS - Cumulative Layout Shift

CLS measures the visual stability of a page. Ever been on a site where you went to tap a button, but an image suddenly loaded and you tapped something else instead? That's a layout shift.

Thresholds:

  • Good: under 0.1
  • Needs improvement: 0.1 - 0.25
  • Poor: over 0.25

Poor CLS is one of the most frustrating experiences for users. Elements that "jump" around the page destroy trust and cause accidental clicks.

How do Core Web Vitals affect sales?

This isn't just about Google rankings. Site speed directly affects conversions and revenue.

Real case studies

Vodafone improved LCP by 31% and saw an 8% increase in sales. Tokopedia (an e-commerce platform) cut LCP by 55% and grew sessions by 23%.

According to Deloitte, a 0.1-second improvement in load time increases conversion rates by 8.4% for retail and 10.1% for travel.

What I've seen in practice

I've tested over 50 business websites over the past 6 months (most of them for clients here in Romania, where I'm based). The results were concerning:

  • 73% had an LCP over 4 seconds on mobile
  • 45% had a CLS over 0.25
  • Only 12% passed all three Core Web Vitals metrics

That means 88% of the sites I tested were delivering a subpar experience. If your site is in that 12% that passes, you already have a massive competitive advantage.

How to check your Core Web Vitals

1. Google PageSpeed Insights

The most accessible tool. Go to PageSpeed Insights, enter your URL, and get a detailed report with scores and concrete recommendations.

Note: test both the desktop and mobile versions. The mobile score is what matters more to Google, and it's usually significantly lower than the desktop score.

2. Google Search Console

If you have Google Search Console set up (and you should), the "Core Web Vitals" section shows you the status of all your pages, based on real user data.

3. Chrome DevTools

Open your site in Chrome, press F12, go to the "Lighthouse" tab, and run an audit. You'll get a full report with metrics and optimization suggestions.

4. Web Vitals Extension

Install the Web Vitals extension for Chrome. It shows you Core Web Vitals in real time on any site you visit.

The most common causes of poor scores

Unoptimized images - the number one culprit

This is the problem I run into most often. 3-5MB photos uploaded straight from the camera, with no compression, no modern format.

Fixes:

  • Use WebP instead of JPEG or PNG
  • Compress images (aim for under 200KB per image)
  • Implement lazy loading - images only load when the user scrolls to them
  • Specify image dimensions in code to prevent layout shift

Excessive JavaScript

Unnecessary WordPress plugins, multiple tracking scripts, JavaScript libraries loaded but never used. Every kilobyte of JavaScript has to be downloaded, parsed, and executed by the browser.

Fixes:

  • Remove plugins you're not actively using
  • Load analytics and chat scripts asynchronously
  • Use tree shaking to eliminate unused code
  • Defer non-critical scripts

Web fonts

Custom fonts look great, but if they're not handled correctly, they block text rendering. The user sees a blank page until the font downloads.

Fixes:

  • Use font-display: swap to show a fallback font instantly
  • Preload critical fonts
  • Stick to 2-3 font variants (don't load 10 different weights)

No browser caching

Without caching, the browser re-downloads the same resources every time a user visits a page. The logo, CSS, scripts - everything from scratch.

Fixes:

  • Set up proper cache headers on your server
  • Use a CDN (Content Delivery Network)
  • Implement Service Workers for advanced caching

Slow server

If your hosting server responds slowly, none of your other optimizations will make up for it.

Fixes:

  • Test your TTFB (Time to First Byte) - it should be under 600ms
  • Choose hosting with servers close to your audience
  • Consider premium hosting like Vercel, Netlify, or a dedicated VPS

Advanced optimizations that make a difference

Preloading critical resources

Tell the browser ahead of time what resources it will need. Using preload tags, the browser starts downloading critical images and fonts before they're actually needed.

Server-side rendering (SSR) or static generation (SSG)

Technologies like Next.js let you generate HTML on the server, so the browser receives content that's ready to display. Compared to a site that builds everything client-side, the speed difference is dramatic.

How I approach Core Web Vitals

When I build a company website or a business website, performance optimization is built in from the first line of code. It's not something I add at the end.

Here are the typical scores I achieve:

  • LCP: under 1.5 seconds (mobile)
  • INP: under 100ms
  • CLS: 0.01 or lower
  • PageSpeed score: 95-100 desktop, 85-100 mobile

These results come from choosing the right technology (Next.js with Server Components), automatic image optimization, preloaded fonts, and fast hosting on Vercel.

Action plan: improve your scores in 7 days

Days 1-2: Audit and prioritize

  • Test all your important pages on PageSpeed Insights
  • Note the issues you find and sort them by impact

Days 3-4: Images

  • Convert all images to WebP
  • Add lazy loading
  • Specify dimensions in HTML

Day 5: JavaScript and CSS

  • Remove unused plugins and scripts
  • Defer non-critical scripts
  • Minify CSS and JavaScript

Day 6: Server and caching

  • Check and optimize your TTFB
  • Configure cache headers
  • Enable Brotli/Gzip compression

Day 7: Verify and monitor

  • Retest all pages
  • Set up alerts in Search Console
  • Document the improvements

Conclusion

Core Web Vitals aren't just technical metrics - they're a direct reflection of the experience you're giving your visitors. A fast site builds trust, reduces frustration, and increases the odds a visitor becomes a customer.

If your scores are below average, don't panic. Most issues have concrete, implementable fixes. If you need professional help, I offer SEO and performance audits that include a detailed optimization plan tailored to your site.