// Case study
When Google Tag Manager became the performance bottleneck
47 tags, duplicate Meta pixels, and consent gaps pushed INP to 480ms, tag governance and deferred loading brought interactivity back under 200ms.
- A healthcare marketing site on WordPress, lead-gen forms, condition-specific landing pages, strict compliance requirements, reported rising bounce on mobile despite acceptable LCP in lab tests. Real-user INP had degraded to 480ms (p75), correlating with campaigns that added more tracking pixels through Google Tag Manager without engineering review.
- GTM container export revealed 47 tags, 31 triggers, and 18 variables, accumulated over three years by performance, SEO, and company teams. We found three Meta Pixel implementations (hardcoded in theme, via GTM, and a leftover plugin), two Hotjar snippets, and a LinkedIn Insight tag firing on DOM ready across every page including logged-in admin (blocked later).
- Problems: marketing insisted all tags stay "active" for attribution; legal required Consent Mode v2 before analytics fired in EU traffic; removing a tag broke a Looker Studio dashboard that depended on a custom dataLayer event nobody had documented.
