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 Personalized recommendations — 1,400ms Time to first byte: 1,400ms. Time to first paint: 1,420ms. Every user, every page view, waits for the slowest API before the browser sees a single byte of HTML — even though four-fifths of the page's data was ready in 200ms. This is the short-board effect, and almost every traditional SSR app pays it. The bucket fills to the height of the shortest plank. The page renders at the speed of the slowest dependency. Streaming SSR is the framework-level fix, and in 2026 it's no longer optional.…