A Lighthouse 95 on a marketing page. CrUX showing 68% of real users experiencing "Poor" LCP. Both measuring the same URL. The page was getting most of its traffic from users in Southeast Asia on mid-range Android devices over 4G. Lighthouse was running on a simulated Moto G4, but with a fast local network and a warm server. The simulated device wasn't the problem — the network conditions and server geography were. This is the gap that field data closes. Lighthouse tells you what's possible in a controlled environment. Field data tells you what's actually happening. Start with what you already have Before building anything, check the Chrome UX Report. PageSpeed Insights shows CrUX data for any URL with enough traffic — real-user LCP, INP, and CLS distributions, broken down into Good / Needs Improvement / Poor buckets. Google Search Console's Core Web Vitals report shows the same data aggregated by page group. CrUX has two limitations worth knowing.…