Load analytics, chat, and third-party scripts with defer/async so they never block rendering.
Render-blocking scripts in <head> stall first paint and the main thread, hurting LCP and INP.
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A synchronous <script> in <head> blocks HTML parsing and rendering. defer runs scripts after parsing in order; async runs independent scripts as soon as they load.
<!-- bad: blocks parsing and first paint -->
<script src="/analytics.js"></script>
<!-- good: non-blocking, runs after parse -->
<script src="/analytics.js" defer></script>In Next.js use next/script with strategy="afterInteractive" or "lazyOnload" for tags like analytics and chat widgets.