Achieving high-performance reactivity in React without compromising the developer experience has always been a key challenge. When building real-time applications designed to display hundreds of millions of rows without noticeable lag, fine-grained reactivity is essential. But when I started my journey at Pigment, neither Recoil, Jotai, nor Zustand were mature enough, and React Compiler was not yet a thing. Let's explore together how we managed to ingest, display, and update huge datasets seamlessly without sacrificing the developer or the user experience.