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Web Performance
2025-10-206 min
Optimizing Core Web Vitals (LCP, INP, CLS) in Next.js 15
Advanced engineering methods to achieve a 100/100 PageSpeed score with React Server Components, streaming SSR and minimal JS bundles.
Julien Kermarec
Ionic Developer Expert (IDE) & Lead Architect
Why Core Web Vitals dictate organic conversion in 2025
Google has made Core Web Vitals a major search ranking signal and user satisfaction metric. An LCP exceeding 2.5s or INP over 200ms directly hurts organic conversion.
Here are the key optimizations I implement during performance audits: - **Fetch Priority on Hero Images**: Always set `priority` on above-the-fold assets. - **Self-hosted Fonts via `next/font`**: Eliminates Google Fonts roundtrips. - **Zero CLS**: Strict layout aspect ratios on all dynamic containers.
#Next.js 15#Core Web Vitals#LCP#INP#React 19