performance-optimization
Web performance standards based on Core Web Vitals (LCP, INP, CLS), with anti-patterns, detection regexes and framework fixes.
- Kind
- Rules
- Works with
- GitHub Copilot
- Source
- Awesome Copilot @ d85f762d6e52
- Path
- instructions/performance-optimization.instructions.md
- License
- MIT
- Jobs
- Review
InstallCopy it from the source repository, or sign in and let the assistant adapt it for your project.
# Performance Standards Comprehensive performance rules for web application development. Every anti-pattern includes a severity classification, detection method, Core Web Vitals metric impacted, and corrective code examples. **Severity levels:** - **CRITICAL** — Directly degrades a Core Web Vital past the "poor" threshold. Must be fixed before merge. - **IMPORTANT** — Measurably impacts user experience. Fix in same sprint. - **SUGGESTION** — Optimization opportunity. Plan for a future iteration. --- ## Core Web Vitals Quick Reference ### LCP (Largest Contentful Paint) **Good: < 2.5s | Needs Improvement: 2.5-4s | Poor: > 4s** Measures when the largest visible content element finishes rendering. Four sequential phases: | Phase | Target | What It Measures | |-------|--------|-----------------| | TTFB | ~40% of budget | Server response time | | Resource Load Delay | < 10% | Time between TTFB and LCP resource fetch start | | Resource Load Duration | ~40% | Download time for the LCP resource | | Element Render Delay | < 10% | Time between download and paint | ### INP (Interaction to Next Paint) **Good: < 200ms | Needs Improvement: 200-500ms | Poor: > 500ms** …