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Most React performance work goes wrong at the first step. Someone notices the app feels slow, guesses which component is to blame, and wraps half the

You call three state setters in a row inside a fetch callback and your component renders three times. Worse, the first of those renders shows the n

Type into a search box that filters ten thousand rows and, in an older React app, the input freezes. Every keystroke kicks off a render of the whole

Every React developer has seen the console warning: "Each child in a list should have a unique key prop." The quick fix is to add key={index}, the

Type into a search box that filters a list of 10,000 items in an older React app and you can feel the problem. Each keystroke triggers a render, the

"React is fast because of the virtual DOM" is one of the most repeated lines in frontend development, and it's only half true. The virtual DOM isn't