Frontend & browser·Rendering and the browser pipeline
the header and layout arrive immediately and the slow part of the page fills in a moment later, in the same response.
Streaming SSR
Also calledstreaming server rendering, progressive rendering
Sending server-rendered HTML in chunks as it becomes ready instead of waiting for the whole page. The shell reaches the browser before the slowest data fetch finishes, so time to first byte stops being hostage to the slowest query. The costs are that you cannot set headers or a status code once the stream has started, and that error handling after the first byte means rendering a fallback in place rather than redirecting.