Summary This skill turns “the app feels slow/janky” into a measured , repeatable , and shippable optimisation program for Expo-managed React Native apps. Non‑negotiables: - Optimise against user-visible KPIs (startup/TTI, scroll FPS, navigation responsiveness, memory growth, p95 network latency). - Profile in production-like builds (release / profile / debugOptimized) — not in dev mode. - Make one change at a time , re-measure, and keep a rollback path. When to use Use when you need to: - Fix slow startup , “white screen”, or delayed time-to-interactive. - Fix scroll jank , dropped frames, sl…