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Core Web Vitals

1) Prerequisites

  • Cloudflare proxy enabled (orange cloud) for developer.sitesignal.app
  • OpenLiteSpeed (CyberPanel) running with QUIC/HTTP/3
  • FTP access to upload /assets and /guides

2) Measure field data

chrome://flags → enable Use First-Party Sets
PageSpeed → https://pagespeed.web.dev/
CrUX via BigQuery or PageSpeed API

3) Improve LCP

  • Preload LCP image or font: <link rel="preload" as="image" href="/hero.webp">
  • Serve images as WebP/AVIF; set explicit width/height
  • Enable OLS cache + ESI where applicable

4) Reduce CLS

  • Reserve space for images, ads, iframes
  • Use CSS aspect-ratio for media

5) Lower INP

  • Defer non-critical JS; avoid long tasks > 50ms
  • Use passive listeners; preconnect critical origins

6) Validate

Re-run PSI; compare field vs lab data. Track over 7 days.