Show HN: I built a sub-500ms latency voice agent from scratch

**Show HN: I built a sub-500ms latency voice agent from scratch**

I built a voice agent from scratch that averages ~400ms end-to-end latency (phone stop → first syllable). That’s with full STT → LLM → TTS in the loop, clean barge-ins, and no precomputed responses.What moved the needle:Voice is a turn-taking problem, not a transcription problem. VAD alone fails; you need semantic end-of-turn detection.The system reduces to one loop: speaking vs listening. The two transitions - cancel instantly on barge-in, respond instantly on end-of-turn - define the experience.STT → LLM → TTS must stream. Sequential pipelines are dead on arrival for natural conversation.TTFT dominates everything...

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