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How to reduce unused JavaScript

Speed1 min readFixes check unused-js

JavaScript that is downloaded but never runs still costs bandwidth, parsing and memory on phones. Split bundles, drop dead plugins and load features on demand.

Step by step, with screenshots: Magento and Adobe Commerce performance: what to change first →

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What a passing site looks like

  • Little unused JavaScript is downloadedwarning · −4 ptseffort M

Unused JavaScript

Why it matters. JavaScript is the most expensive thing a page loads — it must be downloaded, parsed and run. Code that never executes still costs all of that on a phone.

How to fix it.
  1. Delay third-party scripts until interaction (WP Rocket "Delay JavaScript", Shopify: audit installed apps).
  2. Code-split large bundles so each page loads only its own code.
  3. Remove plugins, apps and tags you no longer use.

Filed under Speed & Core Web Vitals. Copy is generated from the same catalogue that scores every report, so what you read here is what the report says.