React.memo is genuinely useful but frequently misapplied. Here is the actual decision framework I use after profiling dozens of components.

These two hooks are often confused, but they solve genuinely different problems. Here is the practical distinction based on actual profiling.

Guessing at performance problems wastes time. Here is the actual workflow I use with the Profiler to find what is genuinely slow before optimizing anything.

Code splitting genuinely reduces initial load time, but only when applied at the right boundaries. Here is what actually worked when I measured it.

Slow list rendering has a small number of genuinely common causes. Here is the diagnostic process I actually use, with the specific fix for each cause.

Context is genuinely convenient but causes specific, measurable performance issues when misused. Here is what I found when profiling context-heavy applications.

Bundle size affects load time directly, but you need to actually measure what is in your bundle before you can meaningfully reduce it. Here is the process I use.

Understanding how React batches state updates explains a lot of confusing render behavior. Here is what is actually happening, based on testing across different scenarios.

This choice is often framed as a performance decision, but the actual measured difference is smaller than commonly assumed. Here is what testing actually showed.

Key prop mistakes cause subtle performance and correctness issues that are easy to miss. Here is what I have found while debugging these specific issues.