At a glance the headline numbers for Third-party share
The share of requests going to third parties.
On the typical site, third parties account for 75.0% of the page.
Distribution & median LCP site count and median LCP at each level of third-party share
Passing LCP by third-party share which level passes the LCP most often
Third-party share 75.0%. p75 75.0%. p99 93.7%. At the low end (0): LCP 1.8s. At the high end (100): LCP 1.6s. computed
Why this matters for the Core Web Vitals, and where to start fixing it
The domain count measures connections. The third-party share measures how much of the page you do not control. Third-party script runs on the same main thread as your own code. A slow tag delays the response to every click, and that lag is your INP. Ads, embeds and consent banners inject late and shift the layout. That is CLS.
A third-party file can grow or change behaviour overnight. It never passes through your build pipeline. Your vitals move while your own code did not change. The higher the share, the more of your Core Web Vitals depends on someone else's release schedule.
How does the third-party share affect the Core Web Vitals?
Third-party share correlates with the INP. With little third-party content: 93% pass the INP. Where third parties dominate: 87%.
Chrome field data from 189,915 sites, representing millions of real page loads. How we measured.