reactwg / react-18
React 18 will include architectural improvements to React server-side rendering (SSR) performance. These improvements are substantial and are the culmination of several years of work. Most of these improvements are behind-the-scenes, but there are some opt-in mechanisms you’ll want to be aware of, especially if you don’t use a framework.
The primary new API is pipeToNodeWritable, which you can read about in Upgrading to React 18 on the Server. We plan to write more about it in detail as it's not final and there are things to work out.
Server-side rendering (abbreviated to “SSR” in this post) lets you generate HTML from React components on the server, and send that HTML to your users. SSR lets your users see the page’s content before your JavaScript bundle loads and runs.
The key part is that each step had to finish for the entire app at once before the next step could start. This is not efficient if some parts of your app are slower than others, as is the case in pretty much every non-trivial app.
