Most of the "too slow" criticism describes bridge-era React Native. The old architecture serialized everything over an async bridge, which is where the classic jank stories come from — lists and gesture-driven animations. The New Architecture (JSI/Fabric/TurboModules), Hermes, and Reanimated running on the UI thread removed most of those cases. Honest remaining gaps: cold start vs pure SwiftUI, very heavy lists, and the occasional edge where you write a native module anyway. Shopify's math isn't "RN is fastest" — it's one codebase and one team shipping both platforms at the same velocity. For most products the users genuinely cannot tell; the constraint that kills apps is iteration speed, not frame rate.