Question 1

What are the mobile Core Web Vitals for developer.mozilla.org?

Accepted Answer

developer.mozilla.org mobile (phone form factor) p75 metrics from Google CrUX: LCP 1477ms (good), INP 128ms (good), CLS 0.000 (good). Mobile reflects real-world conditions for the ~60% of web traffic that's mobile-first.

Question 2

Why are mobile vitals usually worse than desktop for developer.mozilla.org?

Accepted Answer

Mobile devices have constrained CPU + RAM + cellular network conditions versus desktop's wired connection, so mobile often shows slower LCP and higher INP on the same site. CLS varies less by device. Mobile is also Google's primary ranking signal — mobile vitals directly affect search rankings.

Question 3

How current is the mobile CrUX data for developer.mozilla.org?

Accepted Answer

Collection window: 2026-09-22 to 2026-10-19. Google CrUX publishes monthly aggregates derived from 28-day p75 trailing measurements of real Chrome users on phone devices. Refresh cadence is automated.