React Performance: Server — Parallel Fetching. Keywords: parallel fetch component composition. Platform: React/Next.js. Description: Restructure components to parallelize data fetching in RSC. Do: Use component composition for parallel fetches. Don't: Sequential fetches in parent component. Good Example: <Header /><Sidebar /> // both fetch in parallel. Bad Example: const header = await fetchHeader(); return <><div>{header}</div><Sidebar /></>. Severity: Critical.