Performance profiling principles. Measurement, analysis, and optimization techniques.
npxskills add davila7/claude-code-templates--skill performance-profilingLoading…
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 |
| < 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.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or multi-account), or reading/injecting/running secrets via op.
CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Create or update AgentSkills. Use when designing, structuring, or packaging skills with scripts, references, and assets.
Set up and use 1Password CLI (op). Use when installing the CLI, enabling desktop app integration, signing in (single or multi-account), or reading/injecting/running secrets via op.
CLI to manage emails via IMAP/SMTP. Use `himalaya` to list, read, write, reply, forward, search, and organize emails from the terminal. Supports multiple accounts and message composition with MML (MIME Meta Language).