Chrome field data reports poor Largest Contentful Paint
ShipReady received origin-level Chrome UX Report field data with an LCP 75th percentile above 4,000 ms.
Why it matters
A high field LCP value means a substantial share of observed Chrome visits waited longer than the poor-performance threshold for main content to appear.
How ShipReady detects it
What it inspects
ShipReady sends one request to the Chrome UX Report API for the scanned origin and reads the largest_contentful_paint p75 and its open-ended poor histogram bucket.
What triggers a finding
The rule triggers only when CrUX returns an LCP p75 strictly greater than 4,000 ms. Values at the threshold and the middle band are not reported.
What the evidence shows
Google's origin-level Chrome field dataset reported the displayed LCP p75 and poor-bucket share for the trailing field-data window.
Limits of this check
This is origin-level field data, not a measurement of the scanned page. ShipReady does not render the page, identify the LCP element, diagnose a cause, or guarantee coverage for low-traffic origins. Missing API configuration, unavailable data, and absent metrics do not create a finding.
How to fix it
Investigate with page-level tooling
Use browser performance tooling and representative devices to identify the largest rendered element and the page-specific work delaying it.
How to verify the change
Validate improvements with both views
Recheck the deployed origin's field data after sufficient traffic and compare with controlled page-level measurements.
Expected: The origin-level LCP p75 moves out of the poor band.