Early Hints (HTTP 103)

Server-side rendering takes time. If a server takes 300ms to query a database and generate an HTML file, the client sits idle. HTTP 103 Early Hints allows the server to emit an initial response containing Link: </style.css>; rel=preload headers immediately, before the 200 OK HTML payload is ready.

This allows the browser to initiate DNS resolution and TCP handshakes for critical assets during the server "think time", heavily optimizing the critical rendering path.