Every performance guide tells you to lazy-load. Almost none tell you where to stop. Split on your file tree and you trade one big bundle for a hundred tiny chunks and a waterfall of spinners. The real question isn't how to split — it's finding the seams in the user's journey and cutting there.
There's a particular panic I keep running into: a component re-rendered, someone saw it in the profiler, and now they're tearing the architecture apart to stop it. But rendering isn't React's flaw — it's the whole idea. The word you want is optimize, not minimize, and the difference decides whether your app stays maintainable.
A barrel file makes imports look beautiful and can quietly drag half your app into a bundle that only needed one function. Here's what index.ts actually does, when it earns its place, and when it's a trap wearing a clean interface.
Practical techniques for building fast React applications at scale.