At a glance the headline numbers for Tag managers on page
Tag managers present on the page.
87.2% of sites load Google Tag Manager.
The tag managers on page mix who uses what, and how fast each group loads
Tag managers on page. On the fleet: 87.2% google tag manager, 8.7% matomo tag manager, 1.6% tealium iq. 100.0% of sites use at least one google_tag_manager.
Why this matters for the Core Web Vitals, and where to start fixing it
A tag manager is remote code execution for the marketing team. It loads first, then injects whatever the container holds: more scripts, more pixels, more vendors. None of it passes through your build or your code review, and all of it runs on your visitor's main thread.
The manager itself is not the cost. The contents are, and containers only ever grow. Audit the container like a dependency list: every tag has an owner, a purpose and an expiry date, or it goes.
Chrome field data from 189,915 sites, representing millions of real page loads. How we measured.
Live queries (2) — admin only
SELECT 1 AS ok FROM site_metric_bags LIMIT 0;WITH flat AS (
SELECT CAST(p.key AS VARCHAR) AS cat, 1.0::DOUBLE AS n, NULL::DOUBLE AS size, s.crux."desktop".lcp AS cwv_val
FROM sites s, UNNEST(s.entities.providers) AS u(p)
WHERE p.key IS NOT NULL
AND CAST(p.key AS VARCHAR) <> ''
AND p.category = 'tag_managers'
AND regexp_matches(CAST(p.key AS VARCHAR), '^[a-zA-Z0-9_]+$')
),
totals AS (
SELECT cat,
SUM(n) AS fleet_n,
SUM(size) AS fleet_size,
COUNT(*) FILTER (WHERE n IS NOT NULL) AS sample,
COUNT(*) FILTER (WHERE n > 0) AS with_any,
quantile_disc(n, 0.95) AS p95
FROM flat
GROUP BY cat
),
widths AS (
SELECT *,
GREATEST(1, CAST(round(COALESCE(p95, 0)) AS INTEGER)) AS cap,
LEAST(GREATEST(1, CAST(round(COALESCE(p95, 0)) AS INTEGER)), 12 - 1) AS regular_buckets
FROM totals
),
widths2 AS (
SELECT *,
GREATEST(1, CAST(ceil(cap * 1.0 / regular_buckets) AS INTEGER)) AS width
FROM widths
),
binned AS (
SELECT f.cat, f.cwv_val, w.fleet_n, w.fleet_size, w.sample, w.with_any, w.width, w.regular_buckets,
CASE WHEN f.n IS NULL THEN NULL
ELSE LEAST(CAST(FLOOR(f.n * 1.0 / w.width) AS INTEGER), w.regular_buckets)
END AS bucket_idx
FROM flat f
JOIN widths2 w ON f.cat = w.cat
)
SELECT cat, fleet_n, fleet_size, sample, with_any, width, regular_buckets,
bucket_idx,
COUNT(*) AS n,
quantile_disc(cwv_val, 0.5) AS median,
COUNT(*) FILTER (WHERE cwv_val IS NOT NULL) AS total_cwv,
COUNT(*) FILTER (WHERE cwv_val IS NOT NULL AND cwv_val <= 2500) AS good
FROM binned
WHERE bucket_idx IS NOT NULL
GROUP BY cat, fleet_n, fleet_size, sample, with_any, width, regular_buckets, bucket_idx
ORDER BY cat, bucket_idx;