Original Research
Third-Party Script Performance Statistics 2026
A scoreboard of what third-party scripts actually cost your loading score, ranked by measured LCP impact from real-user field data. Every category links to the full study behind the number.
The headline numbers
- 375 KBMedian third-party JavaScript on a mobile page in 2024, versus just 168 KB of first-party JavaScript.Read the study
- 10.2 ptsThe mobile good-LCP penalty on sites running an A/B testing tool, the steepest of any third-party category we measured.Read the study
- 9.5 ptsThe mobile good-LCP penalty on sites running a live-chat widget, the study's clearest, most fixable cost.Read the study
- 63.0%Share of Google Fonts sites with good mobile LCP, versus 72.3% for sites without them, a 9.3-point loading penalty.Read the study
- 8.6 ptsThe mobile good-LCP penalty on sites running embedded third-party widgets, behind only live chat and A/B tools.Read the study
Charts from the studies
Median third-party JavaScript on the mobile page (KB)
Source: HTTP Archive Web Almanac JavaScript chapters, 2020, 2022, and 2024 editions. 50th-percentile values across the HTTP Archive mobile crawl. CNAME-cloaked third parties are not included, so figures are a lower bound. Read the study: Third-Party JavaScript Statistics 2026: 375KB Per Page Good loading (LCP) by third-party category, mobile penalty
Source: PageSpeed Matters analysis of 9.5 million origins with CrUX field data, mobile 75th percentile, mid-2026. Bars scaled to the largest penalty. A/B testing sits at the top of the list. The anti-flicker snippet is the reason its loading cost outruns every other named tool. Read the study: A/B Testing Tool Performance 2026: 10-Point LCP Hit
The growth problem
Cost by category (measured LCP hit)
- A/B Testing Tools Cost 10.2 Points of Good LCP - the Worst of Any Third-Party Category.Read the study: A/B Testing Tool Performance 2026: 10-Point LCP Hit
- Live Chat Costs 9.5 Points of Good LCP.Read the study: Live Chat Widget Speed 2026: 9.5-Point LCP Hit
- Google Fonts Costs 9 Points of Good LCP.Read the study: Google Fonts Performance 2026: 9-Point LCP Cost
- Social Embeds Cost 8.6 Points of Good LCP.Read the study: Social Embed Performance 2026: 8.6-Point LCP Cost
- GTM Costs 5.3 Points of Good LCP - and Barely Moves Anything Else.Read the study: Google Tag Manager Performance 2026: 5-Point LCP Hit
- Cookie Banners Cost 3.7 Points of LCP - Yet Those Sites Pass Core Web Vitals More Often.Read the study: Cookie Banner Performance 2026: 3.7-Point LCP Cost
How this is measured
Every figure on this page is first-party. It comes from the Chrome User Experience Report (CrUX) real-user field data via Google BigQuery, latest release May 2026, spanning up to 13.75 million origins. No third-party estimates or recycled statistics.
Browse all data studiesDownload the data
Every stat on this page with its sample size, source, and study URL.
Cite this page
Third-Party Script Performance Statistics 2026. PageSpeed Matters. https://www.pagespeedmatters.com/resources/statistics/third-party-scripts
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