Encyclopedia Evalica / Observability / Time-to-first-token (TTFT)
Time-to-first-token (TTFT)
/teyem too ferst 'toh.kuhn tee.tee.ef.tee/The latency until the first output token arrives in a streaming response. TTFT heavily influences perceived responsiveness. (noun)
“TTFT worsened after we changed model providers.”
Related Observability terms
- Active observability •
- AI observability •
- Alert / threshold •
- Dashboard •
- Data flywheel •
- Deep search •
- Drift •
- Error rate •
- Feedback loop •
- Logs •
- Model drift •
- Online evaluation (production scoring) •
- P50 / P95 / P99 (Percentiles) •
- Sampling rate •
- Service Level Indicator (SLI) •
- Service Level Objective (SLO) •
- Token usage / cost tracking •
- Topics
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