LLM streaming from scratch: why TTFT, not total time, is the number users feel — and the SSE reader loop

A language model produces its answer one token at a time. You can either buffer — wait for the whole response, then show it — or stream — push each token to the client the moment it's generated and render it immediately. Both finish at the exact same total time . But one of them feels 5–10x faster, and I built a side-by-side race to show exactly why, plus the client reader loop that makes real streaming work. Here's the whole thing. Two latencies, not one Streaming is only interesting because…