Core Web Vitals 2026: INP, LCP, CLS and How to Optimize

Google’s 2026 metric trio#

Metric	Target	What it is
LCP (Largest Contentful Paint)	< 2.5s	How fast the largest element renders
INP (Interaction to Next Paint)	< 200ms	Lag between click/tap and visual response
CLS (Cumulative Layout Shift)	< 0.1	How much the page “jumps” during load

INP replaced FID as the responsiveness metric in March 2024. It’s stricter: not just the first interaction, but the worst across the whole session.

Optimizing LCP#

1. Host in Indonesia for local users — TTFB drops 30-60ms vs Singapore.
2. Preload the hero image with <link rel="preload" as="image" fetchpriority="high">.
3. Image format: AVIF > WebP > JPEG. Astro & Next.js can auto-convert.
4. Self-host fonts or use font-display: swap + preload + subset.
5. Inline critical CSS, defer the rest. Astro handles this automatically.

Optimizing INP (commonly missed)#

INP suffers when the main thread is blocked. Common causes:

• Heavy hydration — large React components hydrate on click. Fix: islands architecture (Astro), or React Server Components (Next.js).
• Long tasks — JS execution > 50ms. Split with scheduler.yield() or requestIdleCallback.
• Forced layout reflow — reading a DOM property right after writing. Use requestAnimationFrame or batch DOM ops.

Optimizing CLS#

1. Set width + height on every <img>.
2. Reserve space for lazy-loaded content (skeletons).
3. Pre-define iframe/embed dimensions.
4. Avoid injecting content at the top of the viewport after initial render.

Why it matters for Indonesian SEO#

Google Indonesia’s ranking algorithm uses Core Web Vitals as a signal — especially for YMYL niches (finance, health, news). Sites with good CWV get a mobile-search boost, and 80%+ of Indonesian traffic is mobile.

Sites that fail CWV also get docked in the “Page Experience” badge.

Results we hit#

For every Astro project we launch:

• Lighthouse Performance: 95–100
• LCP: 1.0–1.5s on 4G
• INP: 50–150ms
• CLS: 0.0

Free performance audit — send us your URL, we’ll return a report with concrete recommendations.