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 INP site count and median INP at each level of third-party share
Passing INP by third-party share which level passes the INP most often
Third-party share 75.0%. p75 75.0%. p99 93.7%. At the low end (0): INP 90ms. At the high end (100): INP 94ms. 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?
Passing INP barely moves across the range: 94% at one end, 92% at the other. This signal does not separate passing sites from failing ones.
The effect is bigger on LCP. With little third-party content, 86% of sites pass it. Where third parties dominate, 80% do.
Chrome field data from 189,915 sites, representing millions of real page loads. How we measured.