React Native's New Architecture — JSI, Fabric, and TurboModules — has been "coming soon" for long enough that some teams wrote it off as vaporware. It shipped. It is now default in new React Native projects. And it meaningfully changes how the framework works at the performance-critical boundaries between JavaScript and native code. This post is not a getting-started guide. It is an honest account of what the New Architecture actually changes in production applications — which performance improvements are real, which problems it does not fix, what the migration involves, and what you need to know before enabling it on an existing app. What the Old Architecture Got Wrong To understand what the New Architecture changes, you need to understand what it replaces. The Old Architecture communicated between JavaScript and native code through a bridge — an asynchronous, serialisation-based message-passing system. JavaScript could not call native code directly.…