What Are Core Web Vitals (And Why They Affect Your Local Rankings)
Core Web Vitals are Google's technical performance benchmarks. A slow site doesn't just frustrate visitors — it gets deprioritised in search results. Here's what the metrics actually mean.
Most local service businesses are not losing rankings because of bad content or weak links. They are losing them because their website is slow, shifts around while loading, or takes too long to respond to a tap. Google measures all three with a set of metrics called Core Web Vitals.
Here is what they measure and what the thresholds actually mean for your business.
What Core Web Vitals are
Core Web Vitals are a set of real-world performance signals that Google uses as part of its page experience ranking signal. They measure how a page actually feels to load — not just how fast files transfer, but how quickly the page becomes useful and how stable it is while rendering.
There are three metrics.
Largest Contentful Paint (LCP)
LCP measures how long it takes for the largest visible element on the page — usually a hero image or headline — to fully render. This is the closest proxy for "how long does it take before the visitor sees something useful."
Thresholds:
- Good: 2.5 seconds or under
- Needs improvement: 2.5–4.0 seconds
- Poor: over 4.0 seconds
Most agency-built local business sites using page builders like Duda, Squarespace, or WordPress with heavy themes run LCP in the 4–8 second range on mobile. That is in the "poor" band.
Cumulative Layout Shift (CLS)
CLS measures visual instability — how much the page elements move around after the initial render. You have experienced poor CLS when you go to tap a button and it jumps just before you touch it, and you end up clicking an ad instead.
Thresholds:
- Good: 0.1 or under
- Needs improvement: 0.1–0.25
- Poor: over 0.25
CLS is caused by images without defined dimensions, web fonts loading after text, and dynamically injected content (ads, banners, cookie notices) that push existing content down.
Interaction to Next Paint (INP)
INP replaced First Input Delay in March 2024. It measures the full responsiveness of a page — how long it takes for the page to visually respond after every interaction (tap, click, keystroke) throughout the entire visit, not just the first one.
Thresholds:
- Good: 200 milliseconds or under
- Needs improvement: 200–500ms
- Poor: over 500ms
Heavy JavaScript frameworks that ship large client-side bundles — common in template-based website builders — consistently produce poor INP scores on mobile devices.
How Core Web Vitals affect search rankings
Google introduced Core Web Vitals as a page experience ranking signal in 2021. The signal uses real-world data from Chrome users, collected via the Chrome User Experience Report (CrUX), not synthetic lab measurements.
This means Google is ranking your site based on how it actually performs for real users on real devices — not how it performs in an ideal test environment with a fast connection.
For local service businesses competing in the same geographic area with similar relevance signals, Core Web Vitals can be a tiebreaker. Two plumbers in the same city with equivalent GBP profiles and similar backlink profiles: the one with a faster, more stable site ranks higher.
Why mobile performance is what actually matters
Google uses mobile-first indexing for all new websites — meaning Google's crawler evaluates your mobile experience as the primary version of your site. Your desktop performance score is largely irrelevant.
Most local service searches happen on mobile. Someone searching "emergency plumber near me" or "hair salon open now" is on their phone. If your site takes six seconds to load on a mid-range Android device, they are hitting the back button and calling your competitor.
How to measure your own scores
Run your site through Google PageSpeed Insights. It pulls both lab data (synthetic test) and field data (real CrUX data if your site has enough traffic). Focus on the field data — that is what Google uses for ranking.
The Google Search Console Core Web Vitals report shows URL-level performance across your entire site and flags pages that need attention.
What a well-built local site looks like
A site built on a modern framework like SvelteKit, with properly sized images, no render-blocking scripts, and web fonts loaded asynchronously, can consistently hit:
- LCP under 1.5s
- CLS under 0.1
- INP under 100ms
Those scores put a site in the top tier of local competitors in almost every market. That is not a minor edge — it is a ranking advantage that compounds with every other local SEO signal on the page.
What to read next
- How to Write Service Pages That Drive Calls — page structure that works alongside strong performance
- How to Rank in Google's Map Pack — the broader local ranking framework Core Web Vitals feeds into