ZenovayTools

CWV Script Impact Audit

Analyze how third-party scripts impact your Core Web Vitals (LCP, INP, CLS). Identify the biggest performance offenders.

How to Use CWV Script Impact Audit

  1. 1Enter your website URL.
  2. 2The tool detects scripts and estimates their CWV impact.
  3. 3Review the LCP, INP, and CLS contribution of each script.
  4. 4Fix render-blocking scripts and optimize the biggest offenders.
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Frequently Asked Questions

What are Core Web Vitals?▾
Core Web Vitals (CWV) are Google's metrics for user experience: LCP (Largest Contentful Paint) measures loading speed, INP (Interaction to Next Paint) measures responsiveness, and CLS (Cumulative Layout Shift) measures visual stability. They affect search rankings.
How does this tool measure script impact?▾
We detect third-party scripts on your page and estimate their impact on each CWV metric based on known performance profiles. These are estimates based on typical script behavior -- actual impact depends on your specific configuration and server setup.
What is a render-blocking script?▾
A render-blocking script is a <script> tag with a src attribute that lacks async, defer, or type="module" attributes. The browser must download and execute these scripts before rendering the page, directly delaying LCP.
What are good CWV thresholds?▾
Google considers LCP good at 2.5s or less, INP good at 200ms or less, and CLS good at 0.1 or less. This tool uses stricter thresholds for script-only impact since scripts are only part of total page load time.
How can I reduce script impact on CWV?▾
Add async or defer to script tags, lazy-load non-critical scripts, use server-side alternatives for advertising pixels, replace heavy analytics with lightweight options like Plausible or Zenovay, and remove unused scripts.
Does this replace PageSpeed Insights?▾
No. This tool focuses specifically on third-party script impact, which is one factor in overall CWV. Use PageSpeed Insights for comprehensive CWV measurement including images, CSS, fonts, and server response time.