Large lists can slow down React apps because rendering thousands of DOM nodes at once is expensive.
To optimize large lists:

1. Use windowing or virtualization
   Render only visible items instead of the whole list.

2. Use React.memo for list items
   Prevent re-rendering of list items that haven't changed.

3. Use pagination or lazy loading
   Fetch and render a limited number of items at a time.

4. Use keys efficiently
   Provide a stable, unique key prop to each item.

5. Debounce scroll handlers
   If list interactions involve scrolling, debounce heavy computations like fetching or UI updates.

Example with virtualization: Using react-window:

import { FixedSizeList as List } from 'react-window';

const MyList = ({ items }) => (
  <List
    height={500}
    itemCount={items.length}
    itemSize={35}
    width={300}
  >
    {({ index, style }) => <div style={style}>{items[index]}</div>}
  </List>
);

This drastically reduces the number of rendered DOM nodes!

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