Performance
Open Performance for measurements collected from visitors’ browsers.
Metrics
| Metric | What it describes |
|---|---|
| LCP | Loading time for the largest content element. |
| INP | Interaction responsiveness. |
| CLS | Unexpected layout movement. |
| FCP | Time until the first content is painted. |
| TTFB | Time until the first response byte. |
Choose a metric in the top strip to update the chart and breakdowns. Timing measurements and CLS use different units.
Percentiles and attention
Percentile views describe the sample distribution. A p75 value means 75% of the samples are at or below that value. Needs attention orders paths by the selected metric’s p75, worst first, and requires at least three samples per path.
Breakdowns
Inspect device, country and browser groups, each with p75 and sample count. Small samples can change sharply; compare equivalent periods before drawing conclusions.
Measurement limits
The tracker uses the Web Vitals library and browser-supported observations. Missing metrics are not zero scores. These are field measurements, not a Lighthouse test, and single-page navigation does not necessarily create a new document measurement. Web Vitals have a separate usage allowance.
Something unclear? Contact support.