What? React has nothing to do with current state of affairs. In fact, React on GitHub currently exists in mere islands, i.e. in Projects and recently in Pull Requests. Most of the frontend is still Web Components[1] paired with Turbo[2] for hot reloading. GitHub is still as slow even with JavaScript disabled, try it yourself. Backend just serves stuff really slow. In fact, there is an alternative GitHub frontend (no affiliation) that feels snappier and is written in React.[3]

With that said, Mitchell complains about outages. These started directly after Microsoft acquisition[4] and are attributed to migration from AWS to Azure.

[1] https://github.blog/engineering/architecture-optimization/ho...

[2] see html source for tags

[3] https://my.githero.app/

[4] https://damrnelson.github.io/github-historical-uptime/