Google Chrome has officially ended support for the First Input Delay (FID) metric, marking a transition to prioritizing Interaction to Next Paint (INP).
The announcement by Rick Viscomi, who oversees web performance developer relations for the Chrome team, confirms INP as the core metric for evaluating interaction responsiveness.
Today's the day: Chrome ends support for FID
If you're still relying on it in Chrome tools, your workflows WILL BREAK
We're all-in on INP!https://t.co/sc6utE44MN
— Rick Viscomi (@rick_viscomi) September 10, 2024
Today’s announcement follows the replacement of FID with INP as a Core Web Vital in May.
The following tools will stop reporting FID data over the next few days:
- PageSpeed Insights
- Chrome User Experience Report (CrUX)
- web-vitals.js
- Web Vitals extension
Background
The move to replace FID with INP stems from limitations in capturing the full scope of interaction responsiveness on the web.
FID only measured the delay between a user’s input and the browser’s response, overlooking other critical phases.
INP takes a more holistic approach by measuring the entire process, from user input to visual updates on the screen.
Transition Period
While the web-vitals.js library will receive a version bump (5.0) to accommodate the change, 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 in the transition, the Chrome team is also retiring the “Optimize FID” documentation, redirecting users to the updated “Optimize INP” guidance.
We're also shutting down the old Optimize FID article
Now with better APIs and metrics, there's no reason to optimize ONLY the input delay phase of an interaction. Instead, focus on the entire UX from input to painthttps://t.co/DMzeFUelfm
— Rick Viscomi (@rick_viscomi) September 10, 2024
What To Do Next
Here are some steps to take to in light of the transition from FID to INP:
- Familiarize yourself with the INP metric by reviewing the official documentation on web.dev. 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 on web.dev 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 that currently rely on the deprecated FID metric to use INP instead. For web-vitals.js users, be prepared for the breaking change in version 5.0.
- If leveraging the CrUX BigQuery dataset, plan to update data pipelines to handle the schema changes, removing FID fields after the 202409 release in October.
By taking these steps, you can ensure a smooth migration to INP.
Featured Image: Mojahid Mottakin/Shutterstock
