Critical Performance Alert: Unpacking the Duplicate RequireJS Script Loading Bug in Magento 2.4.x

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Critical Performance Alert: Unpacking the Duplicate RequireJS Script Loading Bug in Magento 2.4.x

As e-commerce experts focused on Magento migrations and platform optimization, we at Shopping Mover constantly monitor the pulse of the Magento community. A recent GitHub issue (Issue #40527) has brought to light a significant performance and stability concern affecting Magento Open Source and Adobe Commerce versions 2.4.7, 2.4.8, and the 2.4-develop branch. This critical bug involves the duplicate loading of JavaScript modules via RequireJS, leading to slower page loads and potential front-end errors.

The Core Problem: Unintended Double Script Loading

The issue stems from an unexpected behavior within Magento's RequireJS implementation, specifically in the lib/web/mage/requirejs/mixins.js file. The defContext.configure wrapper, designed to synchronize RequireJS contexts, inadvertently forwards the complete configuration object—including deps (dependencies) and callback—to the unbundled $ RequireJS context. This is problematic because the $ context is primarily intended for path resolution, not for loading modules.

Consequently, every module listed in a deps array within requirejs-config.js is loaded twice: once by the default _ context and again by the $ context. This results in duplicate