Chrome Transitions from First Input Delay to Interaction to Next Paint as Core Metric for Interaction Responsiveness
Google Chrome has officially ended support for the First Input Delay (FID) metric, shifting focus to prioritizing Interaction to Next Paint (INP).
The announcement by Rick Viscomi, who manages web performance developer relations for the Chrome team, confirms that INP is now the central metric for evaluating interaction responsiveness.
Rick Viscomi expressed on social media that Chrome tools will no longer support FID, advising users to transition their workflows to focus on INP.
This update follows the replacement of FID with INP as a Core Web Vital earlier in the year.
The following tools will cease reporting FID data in the coming days:
- PageSpeed Insights
- Chrome User Experience Report (CrUX)
- web-vitals.js
- Web Vitals extension
Background
The decision to replace FID with INP is due to FID’s limitations in fully capturing interaction responsiveness on the web.
FID only measured the delay between a user’s input and the browser’s response, missing other important phases.
INP offers a more comprehensive approach by measuring the entire process, from user input to visual updates on the screen.
Transition Period
The web-vitals.js library will be updated to version 5.0 to accommodate this change, while most other tools will stop reporting FID data without a version update.
The CrUX BigQuery project will remove FID-related fields from its schema starting with the 202409 dataset, scheduled for release in October.
To aid developers during this transition, the Chrome team is also retiring the “Optimize FID” documentation and directing users to the updated “Optimize INP” guidance.
Rick Viscomi also announced that the “Optimize FID” article is being phased out in favor of improved APIs and metrics that cover the entire user experience from input to paint.
What To Do Next
Here are steps to take in light of the transition from FID to INP:
- Familiarize yourself with the INP metric by reviewing the official documentation. Understand how INP measures the full lifecycle of an interaction from input to visual update.
- Audit your site’s current INP performance using tools like PageSpeed Insights or real-user monitoring services that support INP. Identify areas where interaction responsiveness needs improvement.
- Consult the “Optimize INP” guidance for best practices on reducing input delay, optimizing event handling, minimizing layout thrashing, and other techniques to enhance INP.
- Update any performance monitoring tools or custom scripts currently relying on the deprecated FID metric to use INP instead. For web-vitals.js users, prepare for the significant changes in version 5.0.
- If using the CrUX BigQuery dataset, plan to update data pipelines to manage the schema changes, removing FID fields after the 202409 release in October.
By following these steps, you can ensure a smooth transition to INP.
Featured Image: Mojahid Mottakin/Shutterstock
