You've just shipped a site. It loads instantly on your machine, looks great, passes your internal checks. Then you run it through PageSpeed Insights and the mobile score comes back at 41. The instinct is to dismiss it. "Google throttles the test." "It's not a realistic environment." "My actual users aren't seeing this." Some of them are. What the Test Is Actually Simulating PageSpeed Insights uses Lighthouse under the hood, and Lighthouse doesn't test on your infrastructure or your device. It simulates a specific user profile: Device : Moto G Power — a mid-range Android phone, not a flagship. This represents the median globally shipped smartphone, not what developers or early adopters carry. Network : 1.6 Mbps download, 150ms round-trip time. That's slow 4G — the kind of connection you get in a moving vehicle, in a rural area, or in a dense urban environment with tower congestion. CPU : 4x slowdown multiplier applied on top of the simulated device.…