The State of Web Vitals

Script initiator

What injected each script: the HTML parser, another script, or inline markup.

Field data PhoneDesktopAll Scope All sites Q1 2026 edition · Desktop field outcomes
Metric LCP INP CLS
1

At a glance the headline numbers for Script initiator

What injected each script: the HTML parser, another script, or inline markup.

4
Categories
In the distribution
40.6%
Fleet share
Top: inline
94.1%
Sites with any
Of inline

18.3% of scripts are injected by other scripts.

The State of Web Vitals · Q1 2026 · 94,910 sites · desktop field datacorewebvitals.io/state-of-cwv
2

The script initiator mix who uses what, and how stable each group is

Median CLS (sites using feature)
0
0.10
0.20
0.30
0.40
0.50
Inline0.0341% of sites
Parser0.0340% of sites
Script0.0318% of sites
Other0.031% of sites
VariantShare of requestsMedian
Inline
41%
0.03
Parser
40%
0.03
Script
18%
0.03
Other
1%
0.03

Script initiator. On the fleet: 40.6% inline, 40.2% parser, 18.3% script. 94.1% of sites use at least one inline.

By count inline leads (40.6%); by bytes it is parser (49.5%). computed

The State of Web Vitals · Q1 2026 · 94,910 sites · desktop field datacorewebvitals.io/state-of-cwv
3

Passing CLS per bucket every category and count level at once - color is the pass rate

1
2
3
4
5
6
7
8
9
10
11
Inline 40.6%
82
80
79
78
79
78
78
75
76
79
72
Parser 40.2%
78
78
78
80
80
78
78
76
73
70
Script 18.3%
80
80
77
76
76
78
76
77
76
77
70
Other 1%
76
77
71
77
71
72
83
73
← few of this category on the pagemany →
60%95%+ of sites passing CLS Faded cells: under 100 sites

Each row is a category, each column its own count bucket (few on the left, many on the right); the cell is the share of those sites passing CLS.

Inline swings the hardest: 82% of sites pass CLS with few, 72% with many. computed

The State of Web Vitals · Q1 2026 · 94,910 sites · desktop field datacorewebvitals.io/state-of-cwv
4

Few vs many - does quantity cost CLS? the pass rate with few vs many of each category

60%70%80%90%100% few → many
Inline 40.6% 82% → 72%
Script 18.3% 80% → 70%
Parser 40.2% 78% → 70%
Other 1% 76% → 73%
% of sites passing CLS · hollow ring = pages with few, solid dot = pages with many

Per category: the pass rate among pages with FEW of it (hollow ring) against pages with MANY (solid dot), worst trend first. Thin buckets are excluded from the endpoints.

More Inline costs the most: the CLS pass rate falls from 82% with few to 72% with many. computed

The State of Web Vitals · Q1 2026 · 94,910 sites · desktop field datacorewebvitals.io/state-of-cwv
5

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

How a script got onto the page predicts when it runs. Parser-discovered scripts are visible to the preload scanner from the first bytes of HTML. Script-injected scripts are invisible until their parent downloads, parses and runs. That is a chain, and every link adds a network round trip.

Tag managers build these chains by design: the manager loads, then injects tags, which inject more tags. Each hop lands late and competes with your page. Flattening one chain often helps more than minifying everything.

Go fix it Avoid chaining critical requests → The case for limiting analytics and tracking scripts → Head vs footer JavaScript →
Related signals Uses @import → Iframe dimensions set → Responsive image markup → Third-party share → Chrome field data from 94,910 sites, representing millions of real page loads · How we measured