# Perf Audit

> Run Lighthouse performance audit with auto-fix for common issues. Use when user wants to check or improve site performance.

- **Type:** Skill
- **Install:** `agentstack add skill-houseofmvps-ultraship-perf-audit`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [Houseofmvps](https://agentstack.voostack.com/s/houseofmvps)
- **Installs:** 0
- **Category:** [Web & Browser](https://agentstack.voostack.com/c/web-and-browser)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [Houseofmvps](https://github.com/Houseofmvps)
- **Source:** https://github.com/Houseofmvps/ultraship/tree/main/skills/perf-audit
- **Website:** https://www.npmjs.com/package/ultraship

## Install

```sh
agentstack add skill-houseofmvps-ultraship-perf-audit
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Performance Audit

Run Lighthouse against the project and fix performance issues.

## Process

### Step 1: Find the URL

- Check if dev server is running (try common ports: 3000, 5173, 4321, 8080)
- Check package.json scripts for dev/start commands
- Ask user for URL if not auto-detected
- If no server running, suggest starting one first

### Step 2: Run Lighthouse

```bash
node ${CLAUDE_PLUGIN_ROOT}/tools/lighthouse-runner.mjs 
```

Parse JSON output for scores and opportunities.

### Step 3: Report Scores & Core Web Vitals

Present all four Lighthouse scores:
- Performance (target 90+)
- Accessibility (target 90+)
- Best Practices (target 90+)
- SEO (target 100)

Report Core Web Vitals with targets:
- **LCP** (Largest Contentful Paint): target `: preload it, use WebP, add fetchpriority="high"
- If it's text: check web font loading, add font-display: swap
- If it's a background image: preload via ``

**CLS too high?** Check diagnostics for layout shift sources:
- Images without width/height → add dimensions (scanner already checks this)
- Dynamic content injected above fold → reserve space with CSS
- Web fonts causing FOUT → add font-display: optional or swap

**Unused resources?** Check `wasted_resources`:
- `unused_js_kb` > 100KB → code splitting or tree shaking needed
- `unused_css_kb` > 50KB → purge unused CSS (PurgeCSS, Tailwind purge)

**Third-party scripts slow?** Check `third_party_impact`:
- Analytics blocking >100ms → defer/async load
- Ad scripts blocking >200ms → lazy load below fold
- Chat widgets → load on user interaction, not page load

### Step 5: Apply Fixes

For each opportunity, apply fixes using Edit tool:

**Performance fixes (high impact first):**
- **Render-blocking resources** → add `defer` or `async` to non-critical scripts
- **Unused JavaScript** → recommend code splitting, dynamic imports, tree shaking
- **Unused CSS** → recommend PurgeCSS or Tailwind purge config
- **LCP image not preloaded** → add ``
- **Images not lazy-loaded** → add `loading="lazy"` to below-fold images
- **Images without dimensions** → add `width` and `height` attributes
- **No preconnect** → add `` for external origins
- **Font display** → add `font-display: swap` to @font-face declarations
- **Third-party scripts** → defer non-essential scripts, lazy load on interaction

**Accessibility fixes:**
- Missing alt text (also caught by SEO scanner)
- Missing form labels → add `` elements
- Low contrast → adjust colors
- Missing landmark regions → add ``, ``, ``

### Step 6: Graceful Degradation

- **No Chrome**: report "Chrome needed for Lighthouse. Install Chrome or Chromium."
- **Lighthouse timeout**: return partial results with warning
- **No dev server**: suggest starting one, or test against production URL

## Key Principle

**Fix, don't just audit.** Identify the specific elements causing problems. Apply every automated fix possible. For build-tool changes (code splitting, tree shaking), provide exact config recommendations.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [Houseofmvps](https://github.com/Houseofmvps)
- **Source:** [Houseofmvps/ultraship](https://github.com/Houseofmvps/ultraship)
- **License:** MIT
- **Homepage:** https://www.npmjs.com/package/ultraship

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-houseofmvps-ultraship-perf-audit
- Seller: https://agentstack.voostack.com/s/houseofmvps
- Browse the marketplace: https://agentstack.voostack.com/browse

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