Senior React Native Performance Engineer

About this role

The Mission We are building a high-stakes mobile experience where "fast" is the baseline and "fluid" is the requirement. We need 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 be responsible for ensuring our app feels like a premium native product while handling complex, real-time financial data. Core Responsibilities 1. Performance & Stability Zero-Lag Navigation: Architect a 1-1 screen transition map (forward and backward) using Native Stack to ensure hardware-accelerated transitions. Frame Rate Optimization: Maintain a locked 60 FPS (or 120 FPS on ProMotion displays) across all lists and complex views. Crash Management: Implement and monitor rigorous error-tracking (Sentry/Crashlytics) to achieve a 99.9% crash-free rate, specifically debugging native-layer memory leaks and JS-thread hangs. 2. Real-Time Data & State Integrity Instant Updates: Engineer a sophisticated data-fetching strategy for "Mission Critical" info (Balance, Transactions, Recipients) that updates seamlessly when moving from background to foreground. Optimistic UI: Implement "Instant-Success" patterns for payments and profile updates, ensuring the UI reflects user actions before the server round-trip is complete. Cache Strategy: Design a robust local caching layer that eliminates loading spinners for returning users. 3. High-Fidelity Interaction Declarative Animations: Build physics-based, interruptible animations using react-native-reanimated that run exclusively on the UI thread. Gesture-Driven Design: Implement "Native-feel" interactions (swipe-to-action, pinch-to-zoom) that respond instantly to touch. Technical Requirements The "Big Three": Expert-level proficiency in react-native-reanimated, react-native-gesture-handler, and react-native-screens. Data Synchronization: Professional experience with TanStack Query (React Query) or SWR for managing server state, polling, and background refetching. The Bridge & Beyond: Deep understanding of the React Native architecture (Bridge vs. Fabric) and the ability to write custom TurboModules in Swift or Kotlin when JS performance hits a ceiling. List Mastery: Proven experience optimizing large datasets using FlashList (Shopify) or highly optimized FlatLists. Profiling Tools: Mastery of Flipper, React DevTools, and iOS/Android native profilers to identify and kill "Jank." Key Performance Indicators (What success looks like) TTI (Time to Interactive): App launch to "ready" state in under 1.5 seconds on mid-range devices. Transition Latency: Zero perceptible lag between screen taps and transition starts. Data Freshness: Critical financial data must be verified/refetched within 200ms of app foregrounding. Bonus Points Experience in the Fintech or Mobile Money space. A portfolio that includes "Offline-First" applications. Contributions to the React Native Open Source ecosystem.