perf-expert

Files (17)

• SKILL.md
• advanced-apis.md · references/
• bundle-optimization.md · references/
• cache-streaming-hydration.md · references/
• core-web-vitals.md · references/
• css-performance.md · references/
• image-font-optimization.md · references/
• lighthouse-ci.md · references/
• modern-browser-apis.md · references/
• network-compression.md · references/
• perf-report-template.md · references/
• react-compiler-perf.md · references/
• resource-hints-priorities.md · references/
• rum-vs-lab.md · references/
• runtime-profiling.md · references/
• third-party-audit.md · references/
• turbopack-build-perf.md · references/

SKILL.md (first lines)

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# Performance Expert Skill

> **APEX-PERF v24.7.0** | Supreme Performance Analysis Skill
> Lighthouse, Bundle Analysis, Core Web Vitals, Runtime Profiling
> **Replaces:** standalone lighthouse skill, apex-perf archive

---

## Overview

The Performance Expert skill provides comprehensive web performance analysis, optimization, and monitoring capabilities. It consolidates 43 specialized performance reference files into 16 focused, production-grade documents covering every aspect of modern web performance for 2026.

**Agent Delegation:**
- `perf-analyzer` (Opus 4.6) -- orchestration, architecture, performance-critical analysis
- `lighthouse-auditor` (Sonnet 4.6) -- Lighthouse CI, audit interpretation, scoring
- `bundle-analyzer` (Sonnet 4.6) -- bundle composition, dependency cost, tree shaking

---

## Commands

| # | Command | Description |
|---|---------|-------------|
| 1 | `/perf-expert` | Load full skill + all references |
| 2 | `/perf-audit` | Run complete performance audit (Lighthouse + Bundle + CWV + Runtime) |
| 3 | `/perf-cwv` | Analyze Core Web Vitals (LCP, INP, CLS, FCP, TTFB, TBT) |
| 4 | `/perf-lighthouse` | Run Lighthouse CI audit with APEX thresholds |
| 5 | `/perf-bundle` | Analyze bundle size, composition, and dependencies |
| 6 | `/perf-runtime` | Runtime profiling: CPU, memory, render, long tasks |
| 7 | `/perf-images` | Image and font optimization audit |
| 8 | `/perf-network` | Network payload, compression, and transfer analysis |
| 9 | `/perf-cache` | Cache strategy, streaming SSR, and hydration analysis |
| 10 | `/perf-css` | CSS performance: containment, content-visibility, animations |
| 11 | `/perf-third-party` | Third-party script audit and optimization |
| 12 | `/perf-react` | React Compiler performance and RSC optimization |
| 13 | `/perf-turbopack` | Turbopack and build performance analysis |
| 14 | `/perf-rum` | RUM vs Lab data strategy and monitoring setup |
| 15 | `/perf-hints` | Resource hints, preloading, and fetch priority audit |
| 16 | `/perf-modern-apis` | Modern browser API adoption (LoAF, Scheduler, Speculation Rules) |
| 17 | `/perf-advanced` | Advanced APIs (WebGPU, WebCodecs, WASM, Compression Streams) |
| 18 | `/perf-report` | Generate comprehensive performance report |
| 19 | `/perf-budget` | Check all performance budgets (bundle, payload, CWV) |
| 20 | `/perf-compare` | Before/after performance comparison |
| 21 | `/perf-ci` | Set up Lighthouse CI + bundle checks in GitHub Actions |
| 22 | `/perf-fix [metric]` | Fix specific metric (lcp, inp, cls, fcp, ttfb, tbt, bundle) |
| 23 | `/perf-checklist` | Print complete performance optimization checklist |

---

## 9-Step Performance Workflow

```
Step 1: MEASURE (Baseline)
  ├── Lighthouse audit (lab data)
  ├── CrUX/RUM data (field data)
  ├── Bundle analysis
  └── Runtime profiling

Step 2: IDENTIFY (Bottlenecks)
  ├── Largest Contentful Paint element
  ├── Interaction to Next Paint handlers
  ├── Cumulative Layout Shift sources
  ├── Long tasks / main thread blocking
  └── Heavy dependencies / unused code

Step 3: PRIORITIZE (Impact Matrix)
  ├── BLOCK: CWV failures, bundle >120KB, Lighthouse <70
  ├── WARN: CWV borderline, bundle >100KB, Lighthouse <85
  └── INFO: Optimization opportunities, modern API adoption

Step 4: OPTIMIZE (Apply Fixes)
  ├── LCP: preload hero, optimize images, streaming SSR
  ├── INP: scheduler.yield(), code splitting, event delegation
  ├── CLS: explicit dimensions, font display, skeleton loading
  ├── Bundle: tree shaking, dynamic imports, dependency replacement
  └── Runtime: virtualization, Web Workers, requestIdleCallback

Step 5: VERIFY (Gate Checks)
  ├── All 30 verification gates must pass
  ├── Lighthouse CI thresholds met
  ├── Bundle budgets within limits
  └── CWV targets achieved

Step 6: MONITOR (Continuous)
  ├── RUM with web-vitals 5.1.0
  ├── CrUX monthly review
  ├── Vercel Speed Insights
  └── Sentry performance monitoring

Step 7: PREVENT (CI/CD Gates)
  ├── Lighthouse CI on every PR
  ├── Bundle size checks
  ├── Performance budgets
  └── Automated regression detection

Step 8: ITERATE (Continuous Improvement)
  ├── Review field data trends
  ├── Adopt new browser APIs
  ├── Update optimization strategies
  └── Refine budgets based on data

Step 9: REPORT (Stakeholder Communication)
  ├── CWV scorecard
  ├── Bundle composition breakdown
  ├── Before/after comparisons
  └── Recommendations with impact estimates
```

---

## APEX Performance Thresholds

### Core Web Vitals Targets

| Metric | Google "Good" | APEX Target | APEX Stretch |
|--------|---------------|-------------|--------------|
| LCP | <= 2.5s | < 1.5s | < 1.0s |
| INP | <= 200ms | < 150ms | < 100ms |

From Nadav011/apex-skills, MIT.

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