React Performance: Bundle Size — Defer Third Party. Keywords: analytics defer third-party. Platform: React/Next.js. Description: Load analytics and logging after hydration since they don't block interaction. Do: Load non-critical scripts after hydration. Don't: Include analytics in main bundle. Good Example: const Analytics = dynamic(() => import('@vercel/analytics'), { ssr: false }). Bad Example: import { Analytics } from '@vercel/analytics/react'. Severity: Medium.