Description
Your app got slow and you cannot say why. Typing in a search box stutters, a click hangs for a beat, a list of a few thousand rows turns scrolling into a slideshow, and the fix you reach for, wrapping things in useMemo and useCallback, changes nothing except the size of the diff. You open the Profiler and it is a wall of colored bars you cannot read. You cannot tell whether React is the bottleneck or the browser is, whether a component re-renders because its state changed or because a parent did, whether the Context you added is quietly re-rendering half the tree on every keystroke. Everyone can make React render the right pixels. Almost nobody on your team can make it render them fast, and prove it. That is the gap, and it is worth money.
This book teaches you to make React fast the way a staff engineer does: by understanding the engine, measuring before you touch anything, and fixing the one thing that was actually slow. It starts where the speed actually comes from, what happens between calling setState and the browser painting a pixel, the render phase and the commit phase, Fiber and why React can pause and discard work. From there you learn to read the Profiler and answer why did this component render, to place state so a change does not cascade through the whole tree, to memoize only where it pays and recognize the far more common case where it does nothing, to keep an interface fluid during expensive updates with concurrent React, to split code and read your own bundle, to render a list of ten thousand rows by drawing forty, and to tell when React is fast but the browser’s own paint is what is slow. Every chapter works one running app, a dashboard called Ledger, from crawling to instant, and every fix is measured, never guessed. There is almost no API trivia here and a great deal about how rendering really works, where time actually goes, and how to prove a change made the app faster instead of just feeling that it did. For the developer who wants to be the one the team calls when the app is slow.
Who this book is for
This book is for: developers who can already ship React that works and now want the skill that separates a senior from a staff engineer, which is making an app feel instant under real data and real load, and who would rather understand what React actually does underneath a component than paste useMemo everywhere and hope it helps.
What you’ll get inside
- Chapter 1: The week Ledger got slow and I could not say why
- Chapter 2: What actually happens when you call setState
- Chapter 3: This re-renders and I cannot see why
- Chapter 4: One change re-renders half the screen
- Chapter 5: I wrapped everything in useMemo and it is still slow
- Chapter 6: The input freezes while I type
- Chapter 7: The first load takes forever
- Chapter 8: What is inside my bundle and why is it so heavy
- Chapter 9: Ten thousand rows and the scroll stutters
- Chapter 10: I optimized React and the interface is still slow
- Chapter 11: How do I prove it actually got faster
- Chapter 12: Who I became after learning to make things fast
