Performance Profiling
Performance profiling principles. Measurement, analysis, and optimization techniques.
Install
$ agentstack add skill-paulojalowyj-openkit-performance-profiling ✓ scanned · ✓ verified — works with Claude Code, Cursor, and more.
Security review
✓ PassedNo issues found. Passed automated security review. · v0.1.0 How review works →
- ✓ Prompt-injection patterns
- ✓ Secret / credential exfiltration
- ✓ Dangerous shell & filesystem operations
- ✓ Untrusted network calls
- ✓ Known-malicious package signatures
What it can access
- ✓ Network access No
- ✓ Filesystem access No
- ✓ Shell / process execution No
- ✓ Environment & secrets No
- ✓ Dynamic code execution No
From automated source analysis of v0.1.0. “Used” means the capability is present in the source — more access means more to trust, not that it’s unsafe.
About
Performance Profiling
> Measure, analyze, optimize - in that order.
Runtime Scripts
Execute these for automated profiling:
| Script | Purpose | Usage | |--------|---------|-------| | scripts/lighthouse_audit.py | Lighthouse performance audit | python scripts/lighthouse_audit.py https://example.com |
1. Core Web Vitals
Targets
| Metric | Good | Poor | Measures | |--------|------|------|----------| | LCP | 4.0s | Loading | | INP | 500ms | Interactivity | | CLS | 0.25 | Stability |
When to Measure
| Stage | Tool | |-------|------| | Development | Local Lighthouse | | CI/CD | Lighthouse CI | | Production | RUM (Real User Monitoring) |
2. Profiling Workflow
The 4-Step Process
1. BASELINE → Measure current state
2. IDENTIFY → Find the bottleneck
3. FIX → Make targeted change
4. VALIDATE → Confirm improvementProfiling Tool Selection
| Problem | Tool | |---------|------| | Page load | Lighthouse | | Bundle size | Bundle analyzer | | Runtime | DevTools Performance | | Memory | DevTools Memory | | Network | DevTools Network |
3. Bundle Analysis
What to Look For
| Issue | Indicator | |-------|-----------| | Large dependencies | Top of bundle | | Duplicate code | Multiple chunks | | Unused code | Low coverage | | Missing splits | Single large chunk |
Optimization Actions
| Finding | Action | |---------|--------| | Big library | Import specific modules | | Duplicate deps | Dedupe, update versions | | Route in main | Code split | | Unused exports | Tree shake |
4. Runtime Profiling
Performance Tab Analysis
| Pattern | Meaning | |---------|---------| | Long tasks (>50ms) | UI blocking | | Many small tasks | Possible batching opportunity | | Layout/paint | Rendering bottleneck | | Script | JavaScript execution |
Memory Tab Analysis
| Pattern | Meaning | |---------|---------| | Growing heap | Possible leak | | Large retained | Check references | | Detached DOM | Not cleaned up |
5. Common Bottlenecks
By Symptom
| 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 |
6. Quick Win Priorities
| 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 |
7. Anti-Patterns
| 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.
Source & license
This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.
- Author: paulojalowyj
- Source: paulojalowyj/openkit
- License: MIT
- Homepage: https://linktr.ee/paulojalowyj
Install and usage instructions live in the source repository linked above.
Reviews
No reviews yet — be the first.
Write a review
Versions
- v0.1.0 Imported from the upstream source.