Website Performance: Core Web Vitals measure user experience, which is exactly why Google uses them for ranking

Page speed matters to Google because it matters to users. The correlation between load time and bounce rate is well-documented: pages that take 5 seconds to load see roughly 90% higher bounce rates than pages loading in 1 second. Core Web Vitals, the three metrics Google uses as ranking signals, capture the parts of load performance users actually notice: how quickly the largest element appears (LCP), how stable the page is as it loads (CLS), and how quickly it responds to interaction (INP). The highest-impact performance improvements for most sites aren't the technically complex ones. Images account for 60 to 80% of page weight on typical sites. Compressing and properly sizing images delivers larger gains faster than JavaScript optimization or CDN configuration. Start there before diving into critical rendering path analysis. Core Web Vitals data comes in two forms: lab data (simulated, from tools like PageSpeed Insights) and field data (real user experiences, from Chrome's data collection). Google uses field data for ranking signals. A page can score perfectly in lab tests and still fail Core Web Vitals in the field if it performs poorly for real users on mobile devices.