When a user requests a page, it can take from 200 to 500ms for the backend server to create the HTML. During that time the browser is idle, waiting for data to arrive. Developers can speed up start render times and the display of useful content by flushing the buffer. Flushing HTML sends a partial HTML response to the browser, which modern browsers can display. Flushing allows the browser to start fetching components and rendering the response while the backend can continue creating the rest of the HTML page.