15 common useEffect mistakes to avoid in your React apps - LogRocket Blog

"The React community seems divided on the useEffect Hook. Often you will hear things like "Stop using useEffect!" - as if it's a bad Hook. But the truth is, the problem is not with the Hook itself, but with how developers use (and overuse) it. useEffect has been abused so much that it's now associated with unnecessary re-renders, wasted computations, and slow apps."

"componentDidMount and componentDidUpdate run synchronously after DOM updates but before browser paint. useEffect runs after the browser has painted the screen. The key distinction is that is non-blocking and runs asynchronously after paint, while class lifecycle methods run synchronously. This timing difference is crucial. If you use useEffect to run effects that should happen before paint, your effects may run too late, causing visual flickers or layout issues."

Hooks run differently than class lifecycle methods: useEffect executes asynchronously after the browser paints, whereas componentDidMount/componentDidUpdate run synchronously before paint. Using useEffect for work that must occur before paint causes visual flicker and layout issues. Overuse of useEffect leads to unnecessary re-renders, wasted computations, and slower apps. Many common mistakes stem from misunderstanding timing, dependencies, and alternatives. Prefer patterns that avoid useEffect when possible and reserve it for side effects that truly need to run after paint. Teams should audit frequent useEffect occurrences and question whether a different approach suits the problem.

Read at LogRocket Blog