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How can I reduce my site's First Input Delay?

Asked on Nov 03, 2025

Answer

Reducing First Input Delay (FID) involves optimizing your site's JavaScript execution and ensuring the main thread is free to handle user interactions promptly. This can be achieved by minimizing long tasks and deferring non-essential scripts.

Example Concept: FID measures the time from when a user first interacts with your site to the time the browser can respond to that interaction. To improve FID, focus on breaking up long JavaScript tasks, using code-splitting, and deferring or asynchronously loading non-critical scripts to keep the main thread available for user input.

Additional Comment:

Identify long tasks using the Performance tab in Chrome DevTools and break them into smaller, asynchronous tasks.
Use "async" and "defer" attributes for script tags to prevent blocking the main thread during page load.
Consider using web workers to offload heavy computations away from the main thread.
Optimize third-party scripts by loading them only when necessary or using a tag manager to control their execution.

✅ Answered with Core Web Vitals best practices.

Ask any question about Performance here... and get an instant response.

How can I reduce my site's First Input Delay?

Asked on Nov 03, 2025

Answer

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