How Can Reducing JavaScript Improve Your React Application's Performance?

At React Summit 2023, Misko Hevery presented compelling strategies for speeding up React applications by reducing the amount of JavaScript required.

His talk centered on the critical issues caused by excessive JavaScript loads on websites, which often lead to poor performance metrics, particularly in Google's Core Web Vitals.

Hevery suggested that the underlying problem is the heavy reliance on JavaScript for client-side rendering and hydration, which are necessary to make server-rendered pages interactive.

Hevery introduced concepts like partial hydration and resumability as solutions to reduce JavaScript overhead.

He explained how breaking a large application into smaller, independently hydrating components—often referred to as "islands"—can enhance performance.

However, he highlighted a significant challenge with this approach: maintaining communication between these isolated components.

To address this, Hevery discussed his work with Quick, a framework designed to allow these islands to communicate efficiently without requiring excessive JavaScript.

Quick achieves this by focusing on resumability and hydration efficiency, allowing components to load interactively only when needed, thus avoiding the overhead of loading and executing JavaScript that isn't immediately necessary.

Through examples and demonstrations, Hevery showed how Quick could wrap React components to make them hydrate conditionally based on user interactions, such as hovering or clicking, rather than on page load.

This method reduces time to interactive, significantly enhancing the user experience by speeding up the perceived and actual load times of web applications.

How have you approached optimizing JavaScript in your projects?