SEO: Core Web Vitals Optimization Guide 2026

Core Web Vitals are Google's page experience signals: LCP, CLS, and INP.
They affect both rankings and conversion rates. A page that loads slowly loses rankings
and loses users before they see the content.

LCP: Largest Contentful Paint (target: under 2.5 seconds)

LCP measures how long it takes for the largest visible element to load.
Usually a hero image, a heading, or a large block of text.

Common causes of slow LCP:

• Large unoptimized hero images (> 200KB)
• Render-blocking resources (CSS or JavaScript that delays page rendering)
• Slow server response time (TTFB over 600ms)

Fixes:

• Compress and convert images to WebP
• Preload the LCP image: <link rel="preload" as="image" href="hero.webp">
• Move non-critical CSS to defer loading
• Use a CDN to reduce server response time

CLS: Cumulative Layout Shift (target: under 0.1)

CLS measures visual stability. A high CLS means elements jump around as the page loads.

Common causes:

• Images without explicit width and height attributes
• Ads or embeds that load after content
• Web fonts that cause layout shifts on load (FOUT)

Fixes:

• Always specify width and height on img tags
• Reserve space for ads before they load
• Use font-display: swap for web fonts

INP: Interaction to Next Paint (target: under 200ms)

INP measures how quickly the page responds to user interactions.

Common causes of high INP:

• Heavy JavaScript executing on the main thread
• Large DOM size (over 1,400 nodes)
• Third-party scripts blocking interaction response

Fixes:

• Defer non-critical JavaScript
• Break up long tasks (over 50ms) into smaller chunks
• Audit and remove unnecessary third-party scripts

---

Core Web Vitals optimization guide for LCP, CLS, and INP: yositeup.com