At a glance the headline numbers for Ad networks on page
Ad networks present on the page.
Google adsense is the most common ad stack, on 72.2% of sites.
The ad networks on page mix who uses what, and how fast each group loads
Ad networks on page. On the fleet: 72.2% google adsense, 15.8% google publisher tag, 4.7% prebid js. 6.8% of sites use at least one google_adsense.
Why this matters for the Core Web Vitals, and where to start fixing it
Ad scripts are the worst-behaved third parties. They run auctions, inject iframes, load creatives and resize their own slots. A late ad slot growing above the content is the textbook CLS failure, and ad JavaScript competes with every interaction for the main thread (INP).
Ads can be carried safely: fixed-size slots reserved before the auction (nothing shifts), lazy loading for slots below the fold, and an early connection to the ad domains so the auction starts sooner instead of later.
How does this affect the Core Web Vitals?
The choice barely moves the INP: 99% pass at best, 95% at worst. This signal does not separate passing sites from failing ones.
The split is bigger on CLS. With Google adsense, 74% of sites pass it. With Prebid JS, 63% do.
Chrome field data from 189,915 sites, representing millions of real page loads. How we measured.