Understanding React Re-Renders: What Triggers Them and Why They Matter

React re-renders occur when state updates trigger component re-rendering down the component tree. A common performance issue happens when state is placed too high in the component hierarchy, causing unnecessary re-renders of child components. The solution involves moving state down to smaller, dedicated components that encapsulate both the state and components that depend on it. This approach is more effective than using React.memo for preventing unnecessary re-renders and leads to better performance and clearer component structure.