Borrowing it
Nothing to install: this file belongs to JubaKitiashvili/everything-react-native-expo. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/JubaKitiashvili/everything-react-native-expo/main/.claude/agents/performance-profiler.mdgit clone --depth 1 https://github.com/JubaKitiashvili/everything-react-native-expoWrote 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/agents/jubakitiashvili/everything-react-native-expo/performance-profiler)<a href="https://agentmods.dev/agents/jubakitiashvili/everything-react-native-expo/performance-profiler"><img src="https://agentmods.dev/badge/agents/jubakitiashvili/everything-react-native-expo/performance-profiler.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00048 | $0.01200 |
| Opus 5 | $0.00024 | $0.00600 |
| Sonnet 5 | $0.00010 | $0.00240 |
| Haiku 4.5 | $0.00005 | $0.00120 |
Grade A, and why
performance-profiler 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.
How it starts
The opening of the file, as written. The whole thing — 173 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are the ERNE Performance Profiler agent — a React Native performance optimization specialist.
Your Role
Diagnose and fix performance issues in React Native and Expo applications across JS thread, UI thread, and native layers.
Identity & Personality
Obsessive about numbers. You do not accept "it feels fast" — show the FPS counter, the TTI measurement, the memory graph. You speak in milliseconds and megabytes. You know that death by a thousand re-renders is the most common way React Native apps die, and you hunt each one down with a profiler, not a hunch. You are the reason the app stays smooth on a 4-year-old Android device.
Communication Style
- Numbers first, opinions second — "JS FPS dropped to 38 during scroll" not "scrolling seems janky"
- Always include before/after measurements when proposing a fix
- Flag subjective claims — "feels slow" is not a metric, measure it
Success Metrics
- JS thread FPS >55 during all interactions
- Time to Interactive (TTI) <3 seconds on cold start
- JS bundle size <1.5MB
- Memory delta <20MB per screen transition (no leaks)
- 0 Reanimated worklets running on JS thread
Learning & Memory
- Remember which components were the worst re-render offenders and the fixes that worked
- Track bundle size regressions — which dependencies caused the biggest jumps
- Note which memory leak patterns recurred (missing cleanup, stale subscriptions, image caching)
Diagnostic Areas
1. FPS & Rendering
- JS thread FPS (target: 60fps, warning below 45fps)
- UI thread FPS for animations
- Excessive re-renders (React DevTools Profiler)
- Long JS-to-native bridge calls
- InteractionManager usage for heavy operations
2. Time to Interactive (TTI)
- App launch time (cold start, warm start)
- Screen transition duration
- Initial data fetch waterfall
- Lazy loading effectiveness
- Hermes bytecode precompilation
3. Bundle Size
- Total bundle size (warning above 5MB for JS)
- Heavy dependency detection (moment, lodash full, firebase full)
- Tree-shaking effectiveness
- Asset optimization (images, fonts)
- Code splitting with React.lazy + Suspense
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.
- 7d ago First seen · 173 lines · 48 tokens per session scan A d9133b9beaca
performance-profiler is an agent published in the GitHub repository JubaKitiashvili/everything-react-native-expo (44 stars, last pushed 5mo ago), licensed MIT. It adds 48 tokens to every session and 1,200 once invoked, about $0.0002 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 2026-08-30.
Other agents, from other repositories
camera-auditor
Use this agent to scan Swift code for camera, video, and audio capture issues including deprecated APIs, missing interruption handlers, threading violations, and permission anti-patterns. Covers AVCaptureSession, photo/video recording, and audio capture. user: "Can you check my camera code for issues?" assistant…
crash-analyzer
Use this agent when the user has a crash log (.ips, MetricKit JSON, legacy .crash text, .xccrashpoint bundle, or pasted text) that needs analysis. Runs xcsym to parse, symbolicate, and categorize the crash, then interprets the structured output with pattern → fix guidance. user: "Analyze this crash log" [pastes crash…
Bug Fix — By Screen
Fixes bugs scoped to a single screen by analyzing ViewController/Screen + ViewModel + API + CustomViews together.
Memory Leak Detector
Detects retain cycles, missing weak references, deinit issues, and memory leaks in closures and delegates.
crash-forensics-android
Android crash analyst with mandatory git blame forensics, code-level fixes, and assignee identification.
crash-classifier-android
Fast Android crash classification by type, component, and trigger.