👀 Views: 41 💬 Answers: 1 📅 Created: 2025-06-14

react performance react-window javascript

I'm currently using `react-window` to efficiently render large lists in my React application, but I'm experiencing important performance optimization when scrolling. I have a list of about 10,000 items, and I'm using the `FixedSizeList` component to render a vertical list. However, when I scroll, the performance seems to lag, and I notice stutters in the rendering. I have tried optimizing the rendering by memoizing the row component with `React.memo`, but it hasn't improved the situation. Here's a simplified version of my code: ```javascript import React, { useCallback } from 'react'; import { FixedSizeList as List } from 'react-window'; const Row = React.memo(({ index, style }) => { return <div style={style}>Item {index}</div>; }); const MyList = ({ items }) => { const itemCount = items.length; const itemSize = 35; const renderRow = useCallback((props) => <Row {...props} />, []); return ( <List height={500} itemCount={itemCount} itemSize={itemSize} width={300} > {renderRow} </List> ); }; export default MyList; ``` One scenario I suspect might be causing the lag is that the `Row` component does not have a unique key prop. Additionally, I'm unsure if I'm using the `itemSize` correctly since items can vary in height. When I try to set a dynamic height, I often get the behavior: `Warning: Failed prop type: Invalid prop `itemSize` supplied to `FixedSizeList`. It should be a number.` I initially thought that using `VariableSizeList` would solve my scenario, but I’m not sure how to implement it without causing the performance to degrade even further. Is there a way to improve the performance of my list rendering, or should I approach this question differently? Any insights into using `VariableSizeList` effectively would also be greatly appreciated!