sxsphinxstack

Skills / Starter / Inspect a web performance waterfall

Starter Web skill

Inspect a web performance waterfall

Inspect a web performance waterfall across redirects, connection setup, request priority, blocking, and dependency chains.

Trace when each resource became discoverable and which dependency kept the critical experience waiting.

Procedure

  1. Capture the target page, device, network, cache state, region, browser, and user journey.
  2. Mark navigation, first byte, render, primary content, interaction, and load milestones.
  3. Inspect redirects, DNS, connection, TLS, request wait, transfer, and server timing.
  4. Follow initiator and dependency chains for critical scripts, styles, fonts, images, and data.
  5. Check priority, preload, preconnect, blocking, serialization, cache, compression, and duplication.
  6. Compare cold and warm loads plus one healthy control.
  7. Test one change at a time and measure user-facing timing, not only bytes.
  8. Save a waterfall analysis report with before-and-after evidence.

Guardrails

  • One lab trace does not represent every field user.
  • Preloading too many resources can delay the real priority.
  • Do not expose authenticated URLs, headers, or personal data in shared traces.

Related skills

  • Inspect a service worker — Inspect a web service worker's registration, scope, lifecycle, caches, fetch behavior, update state, and offline effects.
  • Inspect browser console errors — Inspect browser console errors by preserving page, version, action, source, stack, network, and reproduction context.
  • Inspect a csp report — Inspect a Content Security Policy report by validating source, directive, blocked resource, document context, browser behavior, privacy, repetition…