/performance-audit-websites

name: performance-audit-websites
description: "Diagnose measured runtime and Core Web Vitals."

Performance Audit Websites

Use this skill to keep premium sites fast enough that visual ambition does not punish users. Measure first and optimize the dominant constraint; do not apply framework folklore as proof.

Own measured diagnosis and implementation. Route pre-build numeric budgets, acceptance thresholds, and visual-richness policy to `$performance-budget-lab`.

Workflow

1. Inspect the affected surface, relevant project scripts, target URL and available inspection tooling; reuse existing context. 2. Read [Performance Audit Websites Guide](references/performance-audit-websites-guide.md) before claiming the site is ready. For React or Next.js implementation work, also read [React and Next.js performance](references/react-next-performance.md). 3. Record a reproducible baseline and identify the dominant request, rendering, interaction or layout-shift cost. When optimization is authorized, change the measured bottleneck and compare under matched build/device/cache conditions. 4. Fix issues when they are in scope; otherwise record exact evidence and remaining risk. 5. Summarize commands, URLs, screenshots/checks, changed files, and what was not tested.

Separate field data, controlled lab data, source inspection, and inference. A Lighthouse score from one machine is not a field-performance guarantee; an optimized source pattern is not a measured user improvement.

Scoped execution

Apply the [shared web contract](../website-operating-rules/references/scoped-web-contract.md) once when execution crosses phases; reuse it if already read. Load only the specialist guidance relevant to the requested surface and deliverable.