Page speed

Page speed is the umbrella metric for how quickly a webpage loads. It's composed of several sub-metrics including TTFB (Time to First Byte), FCP (First Contentful Paint), LCP (Largest Contentful Paint), and INP (Interaction to Next Paint).

Page speed is both a user-experience metric and a Google ranking factor (via Core Web Vitals). Slow pages bounce users and lose rankings even with great content. The bounce-rate gap is real and large: visitors abandon ~32% of pages with a 3-second load time vs ~9% of pages with a 1-second load time.

Measurement tools: Lighthouse (Chrome DevTools, lab data) for debugging, PageSpeed Insights for both lab and field data (CrUX), WebPageTest for detailed waterfall analysis, and the CrUX dashboard for aggregated real-user data. Field data — what actual visitors experience — is what Google uses for ranking; lab data is what developers iterate on.

The highest-leverage page-speed fixes: serve via a CDN (Cloudflare, Vercel Edge), use modern image formats (WebP / AVIF), ship server-rendered HTML (SSR / SSG) instead of client-rendered React, minify and split JavaScript bundles, eliminate render-blocking CSS, preload critical fonts. Most of these are framework-level decisions; switching from a CRA-style SPA to Next.js (SSR/SSG) routinely halves LCP without further work.

Page speed compounds with everything else. A faster site converts better, ranks better, and crawls better. Sites at 1.5s LCP rank above sites at 4s LCP with identical content. Page speed is one of the few SEO investments with both immediate (conversion) and long-term (ranking) ROI.