Migrating a production app to React Native's New Architecture

THE PROBLEM

The app was on RN 0.73 with a class-heavy codebase hitting a performance and memory ceiling. The legacy bridge added latency to native interactions, and the old architecture blocked adopting modern RN capabilities. It couldn't be paused — it's a production app real families use every day.

APPROACH

• Upgraded React Native incrementally from 0.73 to 0.84, de-risking each hop with regression passes.
• Enabled the New Architecture (Fabric renderer + Hermes engine) and validated native module compatibility.
• Refactored legacy class components into functional components with hooks to reduce complexity.
• Profiled both the JS and native layers to find and remove render and memory hotspots.

WHAT WAS HARD

• Third-party native modules that hadn't yet adopted the New Architecture.
• Keeping the app shippable throughout — no big-bang rewrite, no feature freeze.
• Preserving native iOS Swift modules and payment flows across the migration.

IMPACT

• Cut app cold-start time from ~25s to ~5s — an 80% reduction.
• Faster rendering and materially improved runtime stability.
• A codebase ready for modern React Native instead of accumulating debt.
• Zero disruption to the live apps on the App Store.

SEE IT LIVE