WebAudits.pro
WebAudits.pro
Primary DatasetSample: 250 B2B SaaS marketing homepages•January 2026

How Much JavaScript Do SaaS Websites Actually Ship?

Benchmarking 250 B2B SaaS marketing homepages for script execution time, tracking pixel bloat, and hydration overhead.

2.4MBMedian Script PayloadJavaScript code transferred over wire
64%Third-Party Tag ShareShare of main thread execution consumed by tracking tags
820msAverage Blocking TimeTotal blocking time recorded on simulated mobile hardware

Executive Summary & Empirical Findings

Modern SaaS marketing pages are increasingly built like full web apps, shipping megabytes of client-side code for simple static copy. We measured the real impact on user experience.

Core Technical Conclusions:

  • The median B2B SaaS homepage in our sample executed 2.4MB of JavaScript before user interaction.
  • Third-party marketing tags (chat widgets, tag managers, analytics) accounted for an average of 64% of total main-thread blocking time.
  • Static-generated marketing sites (Next.js SSG, Astro) loaded significantly faster than client-rendered SPAs on mobile network profiles.

Testing Methodology & Reproducibility

Automated Chrome DevTools Protocol tracing measured script parse, compile, and evaluation times across 250 SaaS marketing domains under controlled network emulation.

Authoritative Standards & Data Sources

Chrome Performance Profiling Guide

Official DevTools guide for analyzing runtime main-thread bottlenecks

W3C Long Tasks API

Web standard for detecting UI thread execution exceeding 50 milliseconds

Grafana K6 Load Testing Engine

Open-source load testing tool for concurrency benchmarking

Related Research Guides & Actionable Analysis

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How to Score 100 on PageSpeed Without Breaking Conversion Tracking

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Sample: 100 live production domains (91 valid)

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We audited 100 digital agency homepages to document real-world performance bottlenecks and structured data adoption.

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