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rn-performance

rn-performance is a skill for Claude Code, Codex from cmaranho/rn-agent-skills. It costs 48 tokens per session (461 once invoked), scanned A, original, MIT.

A guide for finding and improving slow parts of React Native mobile apps. It covers excessive screen updates, scrolling or animation stutter, memory use, startup time, and heavy components or lists.

In plain words
What is it for?
Use it to investigate slow screens, poor scrolling, animation stutter, high memory use, slow startup, or inefficient lists. It helps measure the issue, apply a targeted fix, and measure again.
Why use it?
It helps locate the actual cause of sluggishness through measurement and profiling instead of guesswork. It also includes checking that a fix does not cause the problem to return.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

not rated 2repo 4mo ago A scan 48 tokens original MIT

Good fit Use it to investigate slow screens, poor scrolling, animation stutter, high memory use, slow startup, or inefficient lists. It helps measure the issue, apply a targeted fix, and measure again.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cmaranho/rn-agent-skills/rn-performance
View source ↗ cmaranho/rn-agent-skills
Install

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.

Any agent
npx skills add cmaranho/rn-agent-skills --skill rn-performance
Clone the repo
git clone --depth 1 https://github.com/cmaranho/rn-agent-skills

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for rn-performance

README.md
[![agentmods](https://agentmods.dev/badge/skills/cmaranho/rn-agent-skills/rn-performance/github.svg)](https://agentmods.dev/skills/cmaranho/rn-agent-skills/rn-performance)
Your own site
<a href="https://agentmods.dev/skills/cmaranho/rn-agent-skills/rn-performance"><img src="https://agentmods.dev/badge/skills/cmaranho/rn-agent-skills/rn-performance/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.

agentmods 80×15 button for rn-performance

Your own site · 80×15
<a href="https://agentmods.dev/skills/cmaranho/rn-agent-skills/rn-performance"><img src="https://agentmods.dev/badge/skills/cmaranho/rn-agent-skills/rn-performance.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 461 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00048 $0.00461
Opus 5.5 $0.00019 $0.00184
Sonnet 5.5 $0.00010 $0.00092
Haiku 4.5 $0.00005 $0.00046

Measured 2mo ago against content hash a15604f0e8b2, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rn-performance 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 2mo 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.

skills/rn-performance/SKILL.md · 52 lines

What it actually says

React Native — Performance

Objetivo

Entregar UI fluida e inicialização rápida, otimizando com base em medição, não em suposição.

Quando utilizar

  • Jank em scroll/animação, renders excessivos ou telas lentas.
  • Alto uso de memória ou tempo de inicialização elevado.
  • Revisão de performance de listas e componentes pesados.

Conhecimentos necessários

  • Modelo de threads do RN (JS thread vs UI/main thread).
  • Profiling (ex.: Flipper, React DevTools Profiler, Perf Monitor, Hermes).
  • Memoização (memo, useMemo, useCallback) e integridade referencial.
  • Virtualização de listas e otimização de imagens.

Fluxo de execução

  1. Meça primeiro: reproduza e faça profiling; identifique o gargalo real.
  2. Isole a causa (re-render, trabalho na main thread, lista não virtualizada, imagem grande).
  3. Aplique a correção mínima (memoização, selector granular, virtualização, mover trabalho para a UI thread).
  4. Meça de novo e compare; evite otimização especulativa.
  5. Adicione uma guarda contra regressão quando possível.

Boas práticas

  • Componentes/hooks puros; props referencialmente estáveis.
  • Listas virtualizadas com keyExtractor estável e item memoizado.
  • Anime na UI thread; evite bloquear a JS thread.
  • Lazy load de telas/recursos; imagens dimensionadas e cacheadas.

Armadilhas comuns

  • Otimizar sem medir.
  • Literais inline de objeto/função quebrando memo.
  • index como key em listas.
  • Trabalho síncrono pesado no render ou na main thread.

Critérios de sucesso

  • Gargalo medido antes e depois, com ganho comprovado.
  • Sem jank perceptível no fluxo alvo.
  • Sem re-renders desnecessários no caminho crítico.
Changes

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.

  1. 2mo ago First seen · 52 lines · 48 tokens per session scan A a15604f0e8b2

Subscribe to this mod's changes

rn-performance is a skill published in the GitHub repository cmaranho/rn-agent-skills (2 stars, last pushed 4mo ago), licensed MIT. It adds 48 tokens to every session and 461 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-31.

DebuggingMobile
Related

rn-performance compared with skills from other repositories

rn-performance next to 6 skills from other repositories
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