capability
verified July 2026
Low latency, with the receipts.
Every vendor says low latency. This page is what we mean by it: the number, what it includes, and how to catch us if it drifts.
01
What the figure includes
Our 107 ms is server time to first audio on the production API — gateway, queue, and synthesis, measured under call-shaped load with cloned voices. It is not model-only time, not a staging box, and not a marketing rounding. The p95 is 108 ms: one millisecond of spread on a single stream. Under sixteen concurrent callers the pair is on the load benchmark, stated rather than hidden.
02
Audit it from your own logs
Every utterance returns its own receipt — the ttfa_ms field in the completion metadata. Log it and the latency claim becomes your dashboard, not our marketing.
// the receipt every utterance carries, on every surface
{"ttfa_ms": 107, "audio_ms": 2810}
# log ttfa_ms per utterance, alert on the tail:
# single stream, production API — 107 ms p50 · 108 ms p95
# what your alert should ask: has MY p95 moved?
# if your histogram disagrees with this page, bring it
# to a call — the harness reruns in front of you
03
Why the turn budget cares
Humans hand a conversation back and forth in about 200 ms and interrupt an agent much past a second. Synthesis is the one stage of that budget you can buy down outright — spend 107 ms here and the rest of the second belongs to your LLM. The full stage-by-stage budget is drawn on the customer-support page.
04
Notes — an engineer's checklist
01Is 107 ms the number I will see end to end?
No — it is server time, so your network round trip sits on top. That is stated on every figure because it is the only honest way to publish latency: we measure what we control, you add what you control.
02What does load do to the figure?
Sixteen concurrent callers on one GPU move the pair to 430 ms p50 / 813 ms p95 with zero failed requests — published on the load benchmark with the setup stated. Load costs latency here, not errors.
03How is the figure kept honest over time?
The harness runs against the production endpoint and reruns live on any demo call. Every utterance you synthesize also returns ttfa_ms, so your own logs audit the claim continuously.
See also
Related sheets.
benchmark
5 rules
How we measure TTS latency
The methodology behind every figure on this site: server-time TTFA on the production API under call-shaped load, percentile pairs, published conditions.
benchmark
813 ms
How the API behaves under load
What one GPU does under 16 concurrent callers — 430 ms median, 813 ms p95, zero failed requests — and how the API refuses traffic past absolute capacity.
glossary
107 / 108
Time to first audio (TTFA)
TTFA is the delay from sending text to the first playable audio byte. How it differs from model latency and TTFB, and how to measure it honestly.
glossary
< 1
Real-time factor (RTF)
RTF is synthesis time divided by audio duration. Why RTF below 1 is table stakes, and why time to first audio matters more for conversations.
Your script, this API, thirty minutes — and the recording leaves with you.
Hear it on your own script