Browser & Web Performance · Middle · Question 19 of 75

Why can third-party scripts hurt INP even if they load with `async`?

1async scripts run on a separate thread but block rendering
2Third-party scripts disable compositing
✓Correct answer: Once loaded, they still execute on your main thread and can run long tasks and event listeners

Explanation

async only avoids blocking the parser. Audit third parties, load them later, or replace heavy embeds with facades.

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