You run Lighthouse in Chrome DevTools on a client URL and see Performance 94. You paste the same URL into PageSpeed Insights and the lab Performance score drops to the sixties. The audits look related. The numbers do not. Neither result is “lying.” They ran the same Lighthouse family of audits on different machines, with different throttling behaviour, and often with different cache and extension state. That gap shows up constantly in agency Slack threads and client calls. People then optimis...