Core Web VitalsSimple mode
Loading Timings
Measures TTFB, FCP, and LCP from a single page load so the three metrics are consistent with each other and reflect the same network conditions.
Why it matters
TTFB, FCP, and LCP form a sequential chain — each one cannot be faster than the previous. Measuring them together in one load makes the numbers comparable and reveals where in that chain the slowdown actually sits.
Where to run it
Available automatically in Simple mode.
Can also be explored in more depth from the underlying WebPerf Snippets reference.
Open analyzerWhat you learn from this test
How fast the server responds (TTFB) and where that time is spent
When users first see content (FCP) and whether render-blocking files are delaying it
Which element becomes LCP and whether it is within a good threshold
Common fixes
Improve server response time with caching or a CDN to reduce TTFB
Eliminate render-blocking CSS and JavaScript to bring FCP closer to TTFB
Preload the LCP image or optimize the hero element to close the FCP-to-LCP gap
Resize and compress the LCP image to reduce download time