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Progressive Hydration: An In-depth Analysis of Optimizing JavaScript Performance

This article explores the concept of progressive hydration, a performance optimization technique that prioritizes and defers the loading and activation of JavaScript across user interfaces. We delve into how modern frameworks like Astro, Qwik, and React implement progressive hydration to improve load times and overall application performance.

about

Ehsan Hosseini

Ehsan Hosseini

me [at] ehosseini [dot] info

I work on what AI agents are allowed to do inside companies, and whether you can prove who authorized it. I write about it here, and build it at my company.

How it works?

I write what I learn while building systems that decide what an AI agent is allowed to do. The thinking, the arguments, and the calls about what's true are mine. I use AI to draft, structure, and speed up research, the same way I'd use any other tool. It doesn't decide what I believe.

I check technical claims against primary sources before a post goes out: the specs, the RFCs, the original documentation, not a model's memory of them. When I'm uncertain, I say so. When something is opinion rather than fact, I mark it as one. If I get something wrong, that's on me.

© 2026 Ehsan Hosseini. All rights reserved.