Senior React Native Performance Engineer (Mobile Optimization)

Afriex (YC S20) is building a high-stakes mobile experience that makes it super easy for immigrants to send money home using blockchain technology. We are looking for an engineer who is obsessed with the mechanics of mobile performance—someone who views a dropped frame as a bug and a 2-second loading state as a failure. You will ensure our app feels like a premium native product while handling complex, real-time financial data.

Key Responsibilities

• Frame Rate Optimization: Maintain a locked 60 FPS (or 120 FPS on ProMotion) across all lists and complex views.
• Zero-Lag Navigation: Architect 1-1 screen transition maps using Native Stack to ensure hardware-accelerated transitions.
• High-Fidelity Interaction: Build physics-based, interruptible animations using react-native-reanimated that run exclusively on the UI thread.
• Real-Time Data: Engineer sophisticated data-fetching strategies for "Mission Critical" info (Balance, Transactions) that updates seamlessly when moving from background to foreground.
• Crash Management: Implement rigorous error-tracking (Sentry/Crashlytics) to achieve a 99.9% crash-free rate, debugging native-layer memory leaks.

Requirements

• The "Big Three": Expert-level proficiency in react-native-reanimated, react-native-gesture-handler, and react-native-screens.
• Architecture: Deep understanding of React Native architecture (Bridge vs. Fabric) and ability to write custom TurboModules in Swift or Kotlin.
• Data Sync: Professional experience with TanStack Query (React Query) or SWR for managing server state.
• List Mastery: Proven experience optimizing large datasets using FlashList (Shopify) or highly optimized FlatLists.
• Profiling: Mastery of Flipper, React DevTools, and iOS/Android native profilers to identify and kill "Jank".

Success Metrics (KPIs)

• TTI (Time to Interactive): App launch to "ready" state in under 1.5 seconds on mid-range devices.
• Latency: Zero perceptible lag between screen taps and transition starts.

Nice to Have

• Experience in Fintech or Mobile Money space.
• A portfolio that includes "Offline-First" applications.