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Text to SpeechBenchmarks

Latency

Time to first byte and real-time factor for Lightning v3.1 and Pro.
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Latency

Time-to-First-Byte (TTFB)

TTFB measures the wall-clock delay between sending the synthesis request and the first audio byte arriving on the wire. Lower is better for real-time and conversational use cases.

ModelTTFBConditions
Lightning v3.1 (Standard)~200 ms40 concurrent requests, WebSocket streaming
Lightning v3.1 Pro~200 ms40 concurrent requests, WebSocket streaming, dedicated Pro pool

Real-Time Factor (RTF)

RTF = Audio Duration ÷ Processing Time. Values above 1.0 mean the model produces audio faster than playback. Both Standard and Pro run at 3.3× real-time on NVIDIA L40S, so a 10-second utterance is fully synthesized in ~3 seconds.