mobile-perf

mobile-perf is a skill for Claude Code from berkcangumusisik/claude-code-practices. It costs 22 tokens per session (385 once invoked), scanned A, original, MIT.

A checklist for finding performance problems in React Native mobile apps, including slow lists, unnecessary screen updates, native communication, and image loading.

In plain words
What is it for?
Use it to inspect a React Native source folder and produce a report of performance issues and their severity.
Why use it?
It helps reveal common causes of sluggish scrolling, excessive updates, and slow interactions before they affect users.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: positional $N argument.

Good fit Use it to inspect a React Native source folder and produce a report of performance issues and their severity.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/berkcangumusisik/claude-code-practices/mobile-perf
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 berkcangumusisik/claude-code-practices --skill mobile-perf
Clone the repo
git clone --depth 1 https://github.com/berkcangumusisik/claude-code-practices

Made for: Claude Code.

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 mobile-perf

README.md
[![agentmods](https://agentmods.dev/badge/skills/berkcangumusisik/claude-code-practices/mobile-perf.svg)](https://agentmods.dev/skills/berkcangumusisik/claude-code-practices/mobile-perf)
Your own site
<a href="https://agentmods.dev/skills/berkcangumusisik/claude-code-practices/mobile-perf"><img src="https://agentmods.dev/badge/skills/berkcangumusisik/claude-code-practices/mobile-perf.svg" alt="Measured on agentmods" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 385 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 $0.00022 $0.00385
Opus 5 $0.00011 $0.00192
Sonnet 5 $0.00004 $0.00077
Haiku 4.5 $0.00002 $0.00038

Measured 7d ago against content hash 343f21b9601a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

mobile-perf 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 7d 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/mobile-perf/SKILL.md · 43 lines

What it actually says

React Native Performance Audit

Target: $1 (or src/ if not specified)

1. List Rendering

grep -rn "map.*return\|\.map(" ${1:-src/} --include="*.tsx" | grep -v "test\|spec" | head -20
  • Plain map() in JSX for lists > 10 items → should use FlatList
  • FlatList without keyExtractor
  • FlatList without getItemLayout for fixed-height items (prevents scroll optimization)
  • Missing removeClippedSubviews for long lists

2. Re-render Detection

grep -rn "useState\|useSelector\|useContext" ${1:-src/} --include="*.tsx" | head -20
  • Context consumers re-rendering when unrelated state changes
  • Inline object/array props (style={{ margin: 10 }} recreated every render)
  • Missing React.memo on list items
  • Missing useCallback on functions passed as props

3. Native Bridge Calls

  • Animated values: using JS-driven vs native-driven (useNativeDriver: true)
  • Missing InteractionManager.runAfterInteractions for post-navigation heavy work
  • Synchronous native modules called in render

4. Images

  • Missing resizeMode and explicit dimensions
  • Not using FastImage for remote images
  • Missing progressive loading for large images

Report with severity and code fix for each finding.

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. 7d ago First seen · 43 lines · 22 tokens per session scan A 343f21b9601a

Subscribe to this mod's changes

mobile-perf is a skill published in the GitHub repository berkcangumusisik/claude-code-practices (10 stars, last pushed 4mo ago), licensed MIT. It adds 22 tokens to every session and 385 once invoked, about $0.0001 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 2026-08-31.

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