pi-speedometer

A per-turn speedometer for pi: TTFT(Time-to-first-token), prefill tok/s, decode tok/s, and total wall time.

Pi's built-in footer already shows tokens, cache, cost, context, and model. This extension surfaces the timing numbers it doesn't show.

Status line

After each turn, pi's status area shows:

ttft 1967ms  prefill 412 tok/s  decode 63.8 tok/s  total 14.2s

Commands

• /speed — show recent turns and per-model session averages
• /speed clear — reset history
• /speed csv — dump full history to ~/.pi/pi-speedometer-<timestamp>.csv

Install

pi install npm:pi-speedometer

Or try it without installing:

pi -e npm:pi-speedometer

How it's measured

• TTFT — performance.now() from turn_start to the first text_delta or toolcall_delta (thinking deltas are skipped so TTFT reflects perceived latency on reasoning models).
• Prefill tok/s — (input + cacheWrite) / ttft. cacheRead is excluded because those tokens didn't require real prefill work this turn. cacheWrite is included because those tokens were processed and persisted to cache.
• Decode tok/s — output / (turn_end - first_token).
• Total — wall-clock from turn_start to turn_end, including any tool round-trips inside the turn.

Numbers come from AssistantMessage.usage (provider-agnostic) plus pi's own event timings, so any provider pi supports will report.

License

MIT