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Measure, analyze, optimize - in that order.
Execute these for automated profiling:
| Script | Purpose | Usage |
|--------|---------|-------|
| scripts/lighthouse_audit.py | Lighthouse performance audit | python scripts/lighthouse_audit.py https://example.com |
| Metric | Good | Poor | Measures | |--------|------|------|----------| | LCP | < 2.5s | > 4.0s | Loading | | INP | < 200ms | > 500ms | Interactivity | | CLS | < 0.1 | > 0.25 | Stability |
| Stage | Tool | |-------|------| | Development | Local Lighthouse | | CI/CD | Lighthouse CI | | Production | RUM (Real User Monitoring) |
1. BASELINE → Measure current state
2. IDENTIFY → Find the bottleneck
3. FIX → Make targeted change
4. VALIDATE → Confirm improvement
| Problem | Tool | |---------|------| | Page load | Lighthouse | | Bundle size | Bundle analyzer | | Runtime | DevTools Performance | | Memory | DevTools Memory | | Network | DevTools Network |
| Issue | Indicator | |-------|-----------| | Large dependencies | Top of bundle | | Duplicate code | Multiple chunks | | Unused code | Low coverage | | Missing splits | Single large chunk |
| Finding | Action | |---------|--------| | Big library | Import specific modules | | Duplicate deps | Dedupe, update versions | | Route in main | Code split | | Unused exports | Tree shake |
| Pattern | Meaning | |---------|---------| | Long tasks (>50ms) | UI blocking | | Many small tasks | Possible batching opportunity | | Layout/paint | Rendering bottleneck | | Script | JavaScript execution |
| Pattern | Meaning | |---------|---------| | Growing heap | Possible leak | | Large retained | Check references | | Detached DOM | Not cleaned up |
| Symptom | Likely Cause | |---------|--------------| | Slow initial load | Large JS, render blocking | | Slow interactions | Heavy event handlers | | Jank during scroll | Layout thrashing | | Growing memory | Leaks, retained refs |
| Priority | Action | Impact | |----------|--------|--------| | 1 | Enable compression | High | | 2 | Lazy load images | High | | 3 | Code split routes | High | | 4 | Cache static assets | Medium | | 5 | Optimize images | Medium |
| ❌ Don't | ✅ Do | |----------|-------| | Guess at problems | Profile first | | Micro-optimize | Fix biggest issue | | Optimize early | Optimize when needed | | Ignore real users | Use RUM data |
Remember: The fastest code is code that doesn't run. Remove before optimizing.
performance-profiling is an expert AI persona designed to improve your coding workflow. Performance profiling principles. Measurement, analysis, and optimization techniques. It provides senior-level context directly within your IDE.
To install the performance-profiling skill, download the package, extract the files to your project's .cursor/skills directory, and type @performance-profiling in your editor chat to activate the expert instructions.
Yes, the performance-profiling AI persona is completely free to download and integrate into compatible Agentic IDEs like Cursor, Windsurf, Github Copilot, and Anthropic MCP servers.
Performance profiling principles. Measurement, analysis, and optimization techniques.
Download Skill Package.cursor/skills@performance-profiling in editor chat.Copy the instructions from the panel on the left and paste them into your custom instructions setting.
"Adding this performance-profiling persona to my Cursor workspace completely changed the quality of code my AI generates. Saves me hours every week."
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