Frontend Performance45-70 min
Virtualization for Large Lists
Use virtualization for large tables, feeds, logs, and search results to keep DOM size and render cost under control.
ReactTanStack Virtualreact-window
Prerequisites
- A list or table with hundreds or thousands of rows.
- Stable item height or a strategy for measuring dynamic height.
- Keyboard and accessibility requirements for the list.
1
Plan the implementation
Start by choosing the exact page, route, API, or deployment surface you want to improve. A narrow target makes the implementation measurable and easier to verify.
- Write down the current behavior and the user-facing problem it creates.
- Pick one measurable success signal such as bundle size, latency, error rate, security coverage, or UI responsiveness.
- Identify the files, routes, providers, and environment variables involved.
- Create a rollback note before changing production-sensitive configuration.
2
Set up the required tools
Install or configure only the tools needed for this implementation. Keep config close to the feature so future developers can find the moving parts quickly.
Implementation snippet
npm install @tanstack/react-virtualChecklist
- Dependencies are added to the correct workspace package.
- Environment variables are documented in `.env.example` when needed.
- Local development still starts without production-only secrets.
- The change is small enough to review in one pull request.
3
Implement the core pattern
- Confirm the performance issue is caused by too many DOM nodes.
- Wrap the list in a scroll container with a stable height.
- Use a virtualizer to calculate visible rows.
- Render only virtual rows while preserving total scroll height.
- Test keyboard navigation, selection, and resizing.
Implementation snippet
const rowVirtualizer = useVirtualizer({
count: rows.length,
getScrollElement: () => parentRef.current,
estimateSize: () => 48,
});4
Handle edge cases
Checklist
- The DOM contains only visible rows plus overscan.
- Scrolling stays smooth on lower-end devices.
- Rows keep stable keys when data changes.
- Empty, loading, filtered, and selected states still work.
5
Verify before production
- Run the app locally and test the normal success path.
- Test one failure path, one empty state, and one slow-network or retry path.
- Run the project build and any related unit or integration tests.
- Check browser console, server logs, and network responses for hidden warnings.
- Document the final behavior, commands used, and any follow-up work.