Skills · SkillTesting & SecurityReviewed

benchmark

Measure performance baselines and detect regressions across browser Core Web Vitals (LCP, INP, CLS, page weight), API endpoint latency percentiles, and build/test feedback times, with before/after comparison stored in git-tracked .ecc/benchmarks JSON.

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Kind: Skill
Works with: Claude Code, Codex
Source: affaan-m/ECC @ d3b8a3e90890
Path: skills/benchmark/SKILL.md
License: MIT
Jobs: Testing, Git workflow, Guardrails

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# Benchmark — Performance Baseline & Regression Detection

## When to Use

- Before and after a PR to measure performance impact
- Setting up performance baselines for a project
- When users report "it feels slow"
- Before a launch — ensure you meet performance targets
- Comparing your stack against alternatives

## How It Works

### Mode 1: Page Performance

Measures real browser metrics via browser MCP:

```
1. Navigate to each target URL
2. Measure Core Web Vitals:
   - LCP (Largest Contentful Paint) — target < 2.5s
   - CLS (Cumulative Layout Shift) — target < 0.1
   - INP (Interaction to Next Paint) — target < 200ms
   - FCP (First Contentful Paint) — target < 1.8s
   - TTFB (Time to First Byte) — target < 800ms
3. Measure resource sizes:
   - Total page weight (target < 1MB)
   - JS bundle size (target < 200KB gzipped)
   - CSS size
   - Image weight
   - Third-party script weight
4. Count network requests
5. Check for render-blocking resources
```

### Mode 2: API Performance

Benchmarks API endpoints:

```
1. Hit each endpoint 100 times
2. Measure: p50, p95, p99 latency
3. Track: response size, status codes
4. Test under load: 10 concurrent requests
…