Google Chrome Phases Out First Input Delay: What This Means for Web Developers

Google Chrome has officially discontinued support for the First Input Delay (FID) metric, transitioning to the new Interaction to Next Paint (INP) metric. This shift reflects a move toward a more comprehensive approach to measuring web interaction responsiveness.

What’s Changing?

As of today, Chrome is removing FID as a key performance metric. The change was announced by Rick Viscomi, who leads web performance developer relations for the Chrome team. The core focus now shifts to INP, which evaluates how well a webpage responds to user interactions from the moment of input until visual feedback is presented.

Why the Shift?

The replacement of FID with INP addresses the limitations of the previous metric. While FID measured the time between a user’s action and the browser’s response, it didn’t capture the full user experience. INP offers a more holistic view by assessing the entire interaction lifecycle—from the initial input to the visual update on the screen.

Impact on Tools and Resources

Several tools and resources will soon stop reporting FID data:

• PageSpeed Insights
• Chrome User Experience Report (CrUX)
• web-vitals.js
• Web Vitals extension

The web-vitals.js library will be updated to version 5.0 to support INP, but other tools will cease FID data reporting without requiring an update. Additionally, the CrUX BigQuery project will remove FID-related fields from its schema starting with the October 202409 dataset.

To help developers adapt, the Chrome team is retiring the “Optimize FID” documentation and directing users to the new “Optimize INP” guidelines.

Next Steps for Developers

Here’s how to navigate this transition:

1. Learn About INP: Review the official documentation on web.dev to understand how INP measures the entire interaction process.
2. Audit Your Site: Use tools that support INP, like PageSpeed Insights, to assess your site’s current performance and identify areas for improvement.
3. Follow New Guidelines: Consult the “Optimize INP” guidance for best practices on improving input delay, event handling, and reducing layout thrashing.
4. Update Monitoring Tools: Replace any performance monitoring tools or custom scripts that currently use FID with INP-compatible solutions. Note the changes in the web-vitals.js library.
5. Revise Data Pipelines: For users of the CrUX BigQuery dataset, update data pipelines to accommodate the schema changes, including the removal of FID fields.

By taking these steps, you can effectively transition to INP and ensure your website remains optimized for user interaction and performance.