# Third-party scripts loaded asynchronously or deferred - **Pattern:** `ab-002041` (`performance-deep-dive.network-waterfall.third-party-scripts-async`) - **Severity:** low - **Lifecycle:** active - **Last modified:** 2026-04-18 - **Canonical URL:** https://auditbuffet.com/patterns/ab-002041 - **License:** CC-BY-4.0 — attribute to AuditBuffet Pattern Catalog (https://auditbuffet.com/patterns/ab-002041) ## Why it matters A synchronous third-party `` (no async/defer), blocking page rendering. - **Skip (N/A) when:** Never — third-party scripts should always be async/deferred. - **Cross-reference:** For prefetching third-party domains, see `prefetching-configured`. - **Detail on fail:** `"Google Analytics loaded synchronously — blocks rendering for 400ms"` or `"Chat widget script has no async or defer, loaded in and blocks initial render"` - **Remediation:** Add `async` or `defer` to third-party script tags, or load them dynamically after page load: ```html ``` --- ## External references - iso-25010 time-behaviour Taxons: performance HTML version: https://auditbuffet.com/patterns/ab-002041