Sending HTML in pieces
Streaming server side rendering sends the HTML response in chunks as it is produced, rather than waiting for the whole page to finish. The browser can paint the fast parts of the page while the server is still working on the slow parts.
- The shell, header, and layout flush first.
- Slow sections wrapped in boundaries arrive later in the same response.
- The user sees something useful much sooner.
Suspense boundaries
Streaming pairs with Suspense style boundaries. Each boundary marks a region that can render a fallback now and stream its real content when ready.
- A placeholder spinner shows where data is not loaded yet.
- When that data resolves, the server streams the replacement markup.
- One slow query no longer blocks the entire page.
This improves perceived performance and time to first byte without abandoning server rendering. The cost is more complex infrastructure, since responses are no longer a single buffered blob and edge or proxy layers must support streaming.
Key idea
Streaming server side rendering flushes HTML in chunks behind Suspense boundaries, so the fast shell paints immediately while slow sections stream in later instead of one slow query blocking the whole page.