Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add curiositech/some_claude_skills --skill react-performance-optimizergit clone --depth 1 https://github.com/curiositech/some_claude_skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/curiositech/some_claude_skills/react-performance-optimizer)<a href="https://agentmods.dev/skills/curiositech/some_claude_skills/react-performance-optimizer"><img src="https://agentmods.dev/badge/skills/curiositech/some_claude_skills/react-performance-optimizer/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/curiositech/some_claude_skills/react-performance-optimizer"><img src="https://agentmods.dev/badge/skills/curiositech/some_claude_skills/react-performance-optimizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00074 | $0.02775 |
| Opus 5 | $0.00037 | $0.01388 |
| Sonnet 5 | $0.00015 | $0.00555 |
| Haiku 4.5 | $0.00007 | $0.00278 |
Grade A, and why
react-performance-optimizer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 446 lines — stays where its author put it; the contents beside it link to each section on GitHub.
React Performance Optimizer
Expert in diagnosing and fixing React performance issues to achieve buttery-smooth 60fps experiences.
When to Use
✅ Use for:
- Slow component re-renders
- Large lists (>100 items) causing lag
- Bundle size >500KB (gzipped)
- Time to Interactive >3 seconds
- Janky scrolling or animations
- Memory leaks from unmounted components
❌ NOT for:
- Apps with <10 components (premature optimization)
- Backend API slowness (fix the API)
- Network latency (use caching/CDN)
- Non-React frameworks (use framework-specific tools)
Quick Decision Tree
Is your React app slow?
├── Profiler shows >16ms renders? → Use memoization
├── Lists with >100 items? → Use virtualization
├── Bundle size >500KB? → Code splitting
├── Lighthouse score <70? → Multiple optimizations
└── Feels fast enough? → Don't optimize yet
Technology Selection
Performance Tools (2024)
| Tool | Purpose | When to Use |
|---|---|---|
| React DevTools Profiler | Find slow components | Always start here |
| Lighthouse | Overall performance score | Before/after comparison |
| webpack-bundle-analyzer | Identify large dependencies | Bundle >500KB |
| why-did-you-render | Unnecessary re-renders | Debug re-render storms |
| React Compiler (2024+) | Automatic memoization | React 19+ |
Timeline:
- 2018: React.memo, useMemo, useCallback introduced
- 2020: Concurrent Mode (now Concurrent Rendering)
- 2022: Automatic batching in React 18
- 2024: React Compiler (automatic optimization)
- 2025+: React Compiler expected to replace manual memoization
Common Anti-Patterns
Anti-Pattern 1: Premature Memoization
Novice thinking: "Wrap everything in useMemo for speed"
Problem: Adds complexity and overhead for negligible gains.
Wrong approach:
// ❌ Over-optimization
function UserCard({ user }) {
const fullName = useMemo(() => `${user.first} ${user.last}`, [user]);
const age = useMemo(() => new Date().getFullYear() - user.birthYear, [user]);
return <div>{fullName}, {age}</div>;
}
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 446 lines · 74 tokens per session scan A d20ee5d3329b
react-performance-optimizer is a skill published in the GitHub repository curiositech/some_claude_skills (221 stars, last pushed 5d ago), licensed MIT. It adds 74 tokens to every session and 2,775 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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