Good thresholds are LCP under 2.5 seconds, INP under 200 milliseconds, and CLS under 0.1, measured at the 75th percentile of real users. INP replaced First Input Delay in March 2024.
They're a modest ranking signal, but slow pages lose visitors regardless of ranking.
Why it matters when you launch
Launch traffic is bursty and mostly mobile. Test your landing page on a phone over a slow connection before the big day.