Benchmark

Gives you four ways to catch performance regressions before they ship: page metrics (Core Web Vitals, bundle sizes), API endpoint latency (p50/p95/p99), build times (HMR, tests, Docker), and before/after comparisons. The baseline/compare workflow is the real money feature. Run it before your PR, make changes, run it again, and get a table showing what got faster or slower. Saves baselines to .ecc/benchmarks/ so your whole team works from the same numbers. Pairs well with CI to block PRs that regress performance. If you've ever merged something that "felt fine" but tanked load times in prod, this catches it earlier.

skills.sh installs: 5.5K
GitHub stars: 300.3K
last updated: Aug 21, 2026

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Install

$ npx -y skills add affaan-m/ecc --skill benchmark --agent claude-code

Installs into .claude/skills of the current project.

Files

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