At a glance the headline numbers for LCP origin
Whether the LCP resource is served first-party or third-party.
21.5% of LCP images load from a third-party domain.
LCP origin who uses what, and how fast each group loads
Little daylight between the groups: every variant sits near 1.4s median LCP. computed
Passing LCP per LCP origin which group passes the LCP most often
No variant stands out: pass rates sit between 86% and 86%. computed
Why this matters for the Core Web Vitals, and where to start fixing it
An LCP image on a third-party domain pays the connection tax at the worst possible moment. The DNS lookup, TCP handshake and TLS negotiation for that domain happen before the first byte of the image arrives. The same image on your main domain rides the connection that is already open.
Third-party also means someone else's cache rules and someone else's outages under your most important resource. Self-host the hero if you can. If an image CDN must serve it, preconnect to that domain so the setup happens early instead of inside the LCP.
Chrome field data from 189,915 sites, representing millions of real page loads. How we measured.