Early flushing is a [[performance]] optimisation to increase page load.
Rather than delivering the whole page at once, the blocking assets are delivered first so that the browser can retrieve them immediately. Then the rest of the HTML document is delivered afterwards.
This first phase allows the browser to retrieve things like CSS files in parallel with the server rendering/computing the rest of the document, lowering the overall render time for the user.
The first phase can also render some things above the fold as necessary.
https://www.willhastings.me/posts/speeding-up-page-load-with-early-flush/
![[[Early flushing.png]]](/Early-flushing.png){kind=link}