The State of Web Vitals

Third-party domains

How many distinct third-party domains the page contacts.

Field data PhoneDesktopAll Scope All sites Q2 2026 edition · All devices field outcomes
Metric LCP INP CLS
1

At a glance the headline numbers for Third-party domains

How many distinct third-party domains the page contacts.

7
on the typical site
half of sites sit at or below
11
1 in 4 sites exceed this
the top quarter
35
the heaviest 1%
the long tail
185,486
sites measured
all-device field data

The typical site contacts 7 third-party domains. The heaviest 1% contact 35 or more.

The State of Web Vitals · Q2 2026 · 189,915 sites · all devices field datacorewebvitals.io/state-of-cwv
2

Distribution & median CLS site count and median CLS at each level of third-party domains

0.00 0.04 0.08 0.11 0.15
0.1
0 10744 21487
2–2 3–3 4–4 5–5 6–6 7–7 8–8 9–9 10–10 11–11 12–12 13–13 14–14 15–15 16+
Good (≤0.1) Needs improvement Poor (>0.25) Site count
The State of Web Vitals · Q2 2026 · 189,915 sites · all devices field datacorewebvitals.io/state-of-cwv
3

Passing CLS by third-party domains which level passes the CLS most often

Third-party domainsSitesPassing CLSCLS
2–2 14,735 93% 0.00
3–3 14,643 91% 0.00
4–4 14,511 89% 0.00
5–5 13,612 90% 0.00
6–6 13,499 88% 0.00
7–7 13,033 87% 0.00
8–8 11,899 87% 0.00
9–9 11,134 87% 0.00
10–10 9,381 87% 0.00
11–11 8,090 86% 0.01
12–12 6,705 87% 0.01
13–13 5,603 85% 0.01
14–14 4,574 85% 0.01
15–15 3,730 84% 0.01
16+ 21,487 83% 0.02
Good Needs Improvement Poor Faded rows: under 100 sites

Third-party domains 7. p75 11. p99 35. At the low end (2–2): CLS 0.00. At the high end (16+): CLS 0.02. computed

The State of Web Vitals · Q2 2026 · 189,915 sites · all devices field datacorewebvitals.io/state-of-cwv
4

Why this matters for the Core Web Vitals, and where to start fixing it

Third-party domains are a common Core Web Vitals issue. First of all, each third-party domain needs a new connection. That means time is lost on a DNS lookup, a TCP handshake and a TLS negotiation. If you had served those resources from your main domain, the browser could have re-used the connection that is already open (that is why you want HTTP/3: one fast, re-usable connection for everything you control). When that domain serves a font or a stylesheet, the browser cannot render before the connection is ready. The connection setup delays the LCP.

Also, third-party resources are usually out of your control. They can become a SPOF (single point of failure) when their server is slow or down. They can also change in size or behaviour without your knowledge, and your Core Web Vitals change with them. Self-hosting fixes both problems at once. Preconnect only hides part of the connection cost.

Go fix it Self-host Google Fonts → The case for limiting analytics and tracking scripts → Guide to resource prioritization →
Related signals Responsive image markup → Stylesheet loading mix → Image format mix → Images per page → Chrome field data from 189,915 sites, representing millions of real page loads · How we measured