How does streaming change TTFB versus hydration cost?
PICTURE THIS: RAG CHATBOT
Simple meaning
Streaming can send the shell quickly so TTFB and first paint improve even if a slow widget is still pending.
WHY — Next.js instead of guessing?
Why interviewers care about Next.js:
contrast on Next.js, not two memorised paragraphs.
the developer, then one case where picking wrong hurts.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Streaming can send the
shell quickly so TTFB and first paint improve even if a slow widget is still pending.
- 2Hydration cost remains for
client islands
- 3too many client components
undo the win.
- 4I stream the page
and keep client JS on interactive leaves.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Streaming can send the shell quickly so TTFB and first paint improve even if a slow widget is still pending. Hydration cost remains for client islands