Fetches any public URL server-side and reports only what it can genuinely observe: measured TTFB and transfer size, then the HTML read for render-blocking scripts and stylesheets, images with no reserved dimensions, eager loading, and font setup. Real Core Web Vitals come from the PageSpeed Insights API — CrUX field data where the origin has traffic, Lighthouse lab data otherwise. Where there is no key there are no vitals, because a number derived from response time is not a measurement.
Fetches a URL server-side and reports what it can actually observe: response time, transfer size, and the static causes of slow paints and layout shift. Real Core Web Vitals appear when a PageSpeed key is configured — nothing on this screen is estimated.
