A no-nonsense explainer of LCP, INP and CLS, what they are, how Google measures them, and the handful of fixes that actually move the numbers on a real small-business website.

Core Web Vitals are Google’s three core performance metrics. They affect rankings, affect conversion rates, and are still the single clearest signal of “is this website well-built or not”. Here is what matters in 2026.

The three metrics

LCP: Largest Contentful Paint

How long until the biggest thing on the page (usually a hero image or headline) is visible.

Good: under 2.5s · Poor: over 4s

INP: Interaction to Next Paint

How long from tapping/clicking something to the screen actually responding. Replaced FID in March 2024.

Good: under 200ms · Poor: over 500ms

CLS: Cumulative Layout Shift

How much the page jumps around as it loads. Images without dimensions and late-loading ads are the usual culprits.

Good: under 0.1 · Poor: over 0.25

The real-world fixes that move the numbers

1. Serve correctly sized images in modern formats

The single biggest LCP win for most small-business sites. Convert JPGs and PNGs to WebP or AVIF, serve responsive sizes with srcset, and never ship a 4000-pixel hero image to a 400-pixel phone.

2. Preload the LCP image

<link rel="preload" as="image" href="/hero.webp">

Small change, big LCP impact.

3. Give every image explicit width and height

Stops layout shift dead. This alone can drop CLS from 0.3 to 0.0.

4. Remove unused JavaScript

The average WordPress homepage ships 800 KB of JS that never gets used. Audit your plugins, remove the ones you do not need, and defer the rest.

5. Self-host your fonts (or skip them)

Third-party font loading adds an extra network round-trip and a layout shift. Either self-host with font-display: swap, or use a good system-font stack.

6. Cache aggressively

Static assets should have a 1-year cache header. HTML can have a shorter cache with a good CDN.

What does NOT matter (much)

Obsessing over a 98 vs 100 Lighthouse score.
Micro-optimising Time to First Byte below 400 ms.
Removing every last render-blocking stylesheet.

The 80/20 is: fast images, cached assets, lean JavaScript. Nail those and you are ahead of 95% of small-business sites.

How we build for Core Web Vitals

Every site we ship at Stuffed Monkey Web Design targets:

LCP under 1.8s on 4G mobile.
INP under 150ms.
CLS of 0.

It is not magic, it is just careful engineering applied consistently. If your current site is in the red on any of the three, we offer a fixed-fee performance audit. Get in touch.

Core Web Vitals in 2026: What Actually Matters for Your Small Business Site