Most marketing scripts and cookie banners run on the critical path. They block the main thread, delay first paint, and inject third-party code before the page is interactive.
Consent managers often make this worse by synchronously loading vendors, mutating the DOM repeatedly, and re-hydrating UI after page load. The result is slower LCP, higher TBT, and unstable CLS.

The fix is not fewer scripts, it is better orchestration. Treat consent as infrastructure, load vendors after intent, and keep compliance off the critical path.