Your Page Is Only as Fast as Your Slowest API: The Case for Streaming SSR

You open Chrome DevTools on your product page. The Network tab has exactly one row that matters — the HTML document — and it's been stuck on "Waiting for response" for 1,400ms. From the browser's point of view, the server is a black box that hasn't said a word yet. Pull up the server's APM trace and the black box opens up. Inside that 1.4 seconds, your loader fanned out to five upstream services: Auth check — 30ms Cart count — 50ms Header navigation data — 80ms Product details — 200ms Personaliz