Why is my long video list slow in React?

Use stable unique keys, lazy-load thumbnails, memoize cards with React.memo, paginate or window for very long lists, avoid inline objects as props so memoized cards do not re-render unnecessarily, and profile first to fix the real bottleneck.

Because they let React track which cards changed and update only those. Without stable keys, React cannot match old cards to new ones efficiently, causing many unnecessary re-renders.

Because loading hundreds of thumbnails at once on initial render is slow. Lazy-loading means thumbnails load as they enter the viewport, keeping the initial render fast and saving bandwidth for off-screen images.