Vercel Speed Insights stops recording First Input Delay on November 1

What is changing

Vercel is deprecating First Input Delay (FID) in Speed Insights and will stop recording new measurements for the metric on November 1st, the company announced in a changelog entry published on October 2nd. Speed Insights is Vercel's real-user monitoring product, and the change removes a metric that has already been superseded in the wider web performance landscape.

According to Vercel, the deprecation is largely administrative. No action is needed from customers, Real Experience Scores will not change, and FID data that has already been collected remains viewable in the product. The only thing that ends is the collection of new FID measurements after the cutoff date.

Why the impact is small

The transition is low-friction because Speed Insights has not depended on FID for its responsiveness reporting for some time. Vercel notes that it already uses Interaction to Next Paint (INP) as the responsiveness metric inside the Real Experience Score, and INP is the Core Web Vital that replaced FID.

FID versus INP

First Input Delay measured the gap between a user's very first interaction with a page — a click, tap, or keypress — and the moment the browser began processing that input. Its weakness was in the name: it only looked at the first interaction, so a page could respond sluggishly to every subsequent click and still post a healthy FID figure.

Google, which maintains the Core Web Vitals, retired FID in favour of INP in March 2024. INP instead evaluates the latency of all qualifying interactions over the lifetime of a page visit and reports a value close to the worst of them, giving a fuller picture of how responsive a site feels in practice. Because it considers more interactions, INP is generally a stricter test than FID ever was. Vercel's deprecation simply aligns its tooling with that newer baseline.

What Vercel customers should do

In practical terms, Vercel says there is nothing to migrate or reconfigure. The main consequence lands on anyone who has built dashboards, alerts, or internal reports around FID: after November 1st those numbers will go stale, since no fresh measurements will arrive. Teams in that position should shift their monitoring to INP, which Speed Insights continues to collect and which already feeds the Real Experience Score.

Vercel points readers to its Speed Insights metrics documentation for further details on the change.

Why it matters

FID has been absent from the Core Web Vitals since INP replaced it, so a vendor dropping it is housekeeping rather than a shift in measurement philosophy. Still, it is a concrete deadline worth noting. For Vercel customers, INP is now unambiguously the responsiveness number to watch, and after November 1st it will be the only one being recorded. Anyone still citing FID in performance budgets, service-level targets, or stakeholder reporting has a fixed date by which to finish moving over, and the existing FID history remains available as a reference point while that migration happens.