Magento 2 RequireJS Bug: Duplicate Script Loading Fix

Verify: Open your browser's DevTools (Network tab) on a product page and filter by JS. Look for duplicate script loads as described above.
Stay Updated: Ensure your Magento instance is updated to the latest patch release once this fix is officially integrated.
Consider Patching: For immediate relief, consider applying the proposed fix as a temporary patch, but always test thoroughly in a staging environment.
Performance Audit: Regularly conduct performance audits. Issues like this highlight the importance of continuous monitoring and optimization.

Code snippet illustrating the proposed fix for Magento's RequireJS mixins.js bug

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

Magento 2 Performance Drain: Unmasking and Fixing the RequireJS Duplicate Script Loading Bug

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

The Core Problem: Unintended Double Script Loading