---
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. Run the narrowest meaningful checks for the risk: visual, mobile, accessibility, performance, forms, media, SEO, analytics, deployment, or handoff.
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.