React Performance: Async Waterfall — Suspense Boundaries. Keywords: suspense streaming boundary. Platform: React/Next.js. Description: Use Suspense to show wrapper UI faster while data loads. Do: Wrap async components in Suspense boundaries. Don't: Await data blocking entire page render. Good Example: <Suspense fallback={<Skeleton />}><DataDisplay /></Suspense>. Bad Example: const data = await fetchData(); return <DataDisplay data={data} />. Severity: High.