Senior React Native Performance Engineer

🌍 Remote, USA 🎯 Full-time 🕐 Posted Recently

Job Description

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

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.

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.

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.

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."

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.