Impact of Fibr Script using GTM
See how the Fibr Script performs across key metrics like FCP, LCP, and Total Blocking Time if placed using Google Tag Manager.
Though the SDK can be inserted using GTM but we’d recommend avoiding GTM for adding the script, as it could lead to issues like flickering or slower load times, which might affect the overall site performance.To see the impact, we have put together a study evaluating the impact of adding scripts of using both the methods on critical website performance metrics.
Avoid injecting the Fibr script through Google Tag Manager since it creates an extra hit of roughly 16% on FCP, 5% on LCP and 24% on the TBT compared with keeping the same script directly in the <head> tag.
Overall Score
First Contentful Paint (FCP)
0.99 s
1.15 s
+160 ms (+16%)
Largest Contentful Paint (LCP)
2.21 s
2.31 s
+100 ms (+5%)
Total Blocking Time (TBT)
587 ms
726 ms
+139 ms (+24%)
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