What Exactly Are Core Web Vitals?
Core Web Vitals are a set of standardized performance metrics created by Google to evaluate real-world user experience. They focus on loading speed, responsiveness, and visual stability — the three pillars that determine how “fast” and “smooth” a site feels. These aren’t technical trivia. They directly influence search rankings, user satisfaction, and ultimately your bottom line.
For founders, understanding these metrics helps you ask better questions, evaluate development work, and spot issues before they become expensive problems.
1. Largest Contentful Paint (LCP)
LCP measures how long it takes for the most meaningful content on a page — often the hero image, headline, or banner — to become visible. Users form an impression of speed within the first few seconds, and LCP heavily influences that perception.
When your LCP is slow, everything feels slow. Even if the rest of your site is optimized, a large hero image or slow server can drown the experience.
- Good: Under 2.5 seconds
- Common issues: unoptimized images, render-blocking scripts, slow servers, heavy fonts
- Founder insight: Ask developers whether images are being lazy-loaded, compressed, and served in modern formats like WebP.
2. Interaction to Next Paint (INP)
INP is the modern replacement for FID (First Input Delay). Instead of measuring just the first interaction, INP evaluates the responsiveness of all interactions — clicks, taps, input fields, and more.
A low INP means your site reacts quickly every time the user interacts. A high INP means your UI feels laggy, giving the impression that the product is poorly engineered.
- Good: Under 200ms
- Common issues: heavy JavaScript bundles, too many animations, unnecessary third-party scripts
- Founder insight: Ask developers if they're code-splitting or removing unused libraries.
3. Cumulative Layout Shift (CLS)
CLS measures how much elements move around while a page loads. Layout shifts create frustration because users expect stable content. A shifting interface feels broken, unreliable, and sometimes scammy — especially when buttons move.
Google heavily penalizes high CLS because it directly harms usability.
- Good: Below 0.1
- Common issues: images without width/height, ads that push content down, injected widgets
- Founder insight: Always ensure design teams provide dimension hints for images and components.
Why Core Web Vitals Matter for Your Business
Google doesn’t just use Core Web Vitals for ranking — they use them to ensure the web feels usable. When your site performs poorly, two things happen:
- Your ranking potential drops, making SEO harder and more expensive.
- Your conversion rates drop because users abandon slow or unstable pages.
Many founders underestimate how performance affects revenue. A 1-second delay can reduce conversions by 7–20% depending on industry. High-performing companies treat performance as a product feature.
Practical Steps Founders Can Take
- Request monthly performance reports from your engineering team.
- Ensure marketing teams avoid uploading oversized images.
- Minimize third-party scripts (analytics, ads, widgets).
- Use a modern hosting provider with global CDN support.
- Measure performance on real devices — not just desktops.
Tools to Test Your Website’s Core Web Vitals
Paste your page URL into these tools to identify real performance issues:
