Core Web Vitals & Performance Scanner
Measure real-user Core Web Vitals where CrUX data is available, combine them with Lighthouse lab diagnostics, and inspect the page itself for slow TTFB, render-blocking CSS/JavaScript, large payloads, fonts, caching, compression and heavy assets.
Preparing…
Preparing audit…
Performance score–LOFT 33 weighted score
LCP–field preferred
INP–CrUX field metric
CLS–field preferred
TTFB–field/lab/direct
Page resources–inspected transfer payload
–Performance health score
Performance overview
Core Web Vitals
Loading
Code & rendering
Assets & delivery
Measurement model
CrUX metrics are real-user 75th-percentile field data when available. Lighthouse values are synthetic lab diagnostics. INP is only shown as a field metric; Lighthouse TBT is kept separate as a responsiveness diagnostic.
CrUX metrics are real-user 75th-percentile field data when available. Lighthouse values are synthetic lab diagnostics. INP is only shown as a field metric; Lighthouse TBT is kept separate as a responsiveness diagnostic.
Highest-priority findings
Core Web Vitals & lab metrics
Lighthouse diagnostics
| Diagnostic | Value | Score |
|---|
PageSpeed opportunities
JavaScript & CSS
| Resource | Type | Status | Size | Loading | Compression | Cache |
|---|
Assets
| Resource | Type | Status | Size | TTFB | Origin | Signals |
|---|
Fonts
| Font resource | Status | Size | Preloaded | Cache |
|---|
Caching & delivery
| Resource | Type | Cache assessment | max-age | Cache-Control | Content-Encoding |
|---|
Prioritised findings
Warnings & limitations
Interpretation
Field data can be unavailable for low-traffic URLs. Direct TTFB and resource timings are measured from the scanner server, so geography and CDN routing can differ from your visitors. Use the findings to prioritise investigation and validate important changes with repeat Lighthouse tests and real-user monitoring.
Field data can be unavailable for low-traffic URLs. Direct TTFB and resource timings are measured from the scanner server, so geography and CDN routing can differ from your visitors. Use the findings to prioritise investigation and validate important changes with repeat Lighthouse tests and real-user monitoring.