Web Performance

Critical Rendering Path

The browser's step-by-step pipeline from bytes to visible pixels — DOM, CSSOM, render tree, layout, and paint — why CSS and JavaScript block rendering, the three optimization levers, and how it drives FCP, LCP, and Googlebot rendering. The hub for render-blocking resources.

4 nested guides inside Critical Rendering Path

Web Performance Tools

The three tools that measure web performance — Google Lighthouse (lab), the Chrome UX Report/CrUX (field), and PageSpeed Insights (both in one UI). Which one Google ranks on, and which to use for what job.

6 nested guides inside Web Performance Tools

Back/Forward Cache (bfcache)

What the back/forward cache is — the browser feature that freezes a whole page in memory for instant Back/Forward navigation — how it differs from the HTTP cache, what blocks eligibility, how to test it, and its real (indirect) relationship to Core Web Vitals and SEO.

HTTP/2 and HTTP/3

What HTTP/2 and HTTP/3 are, how QUIC reduces (not eliminates) head-of-line blocking, and what they mean for SEO — Google says no ranking boost, Googlebot's docs don't list HTTP/3, and the real payoff is indirect via Core Web Vitals.

Speculation Rules API

What the Speculation Rules API (prefetch and prerender) actually is, whether it affects SEO, crawling, or rankings, and how to implement it without inflating your analytics.

Caching for SEO

How browser and server caching with Cache-Control, ETags, and CDNs improves performance and Core Web Vitals, and the caching pitfalls that affect crawling.

CDN and SEO

How a CDN affects SEO — faster TTFB, better Core Web Vitals, edge caching, and geo-distributed delivery — and what to watch for (cache headers, URL canonicalization, HTTPS configuration).

Font Loading

How web font loading affects Core Web Vitals like CLS and LCP, font-display strategies, preloading fonts, and reducing layout shift from font swaps.

Lazy Loading

How lazy loading images and iframes improves Core Web Vitals, the loading attribute, the SEO risks of lazy-loading above-the-fold content, and how Googlebot renders deferred content.

Resource Hints

How preload, preconnect, dns-prefetch, and prefetch resource hints speed up page loads and improve Core Web Vitals, and when to use each one.

Web Vitals

Web Vitals is Google's initiative for unified page-experience quality signals. Here's the full picture — what the initiative covers, which metrics are "Core" (and rank), which are diagnostic, and why your lab score and field data disagree. The hub for the supplementary metrics that sit under Core Web Vitals.

10 nested guides inside Web Vitals