Stream caption latency is the time between a streamer speaking and the caption appearing on screen. Top cloud-based tools deliver captions in 1.5-2.0 seconds end-to-end, while browser-based tools range from 3-8 seconds. Latency under 2 seconds is considered the threshold for natural, conversational captioning.
| Tool Type | Avg. Latency | Example |
|---|---|---|
| Cloud (Deepgram-based) | 1.5-2.0s | StreamTranslate |
| Cloud (Whisper-based) | 2.5-4.0s | Various |
| Browser Web Speech API | 3-6s | Stream CC |
| On-device (LocalVocal) | 4-8s | OBS plugin |
Caption latency above 3 seconds feels disconnected from the speaker. Viewers struggle to match captions to gameplay, reactions, or jokes. Under 2 seconds feels natural — captions track the streamer in real time.
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