Kimi K3.1 Pro Highspeed

Kimi K3.1 Pro Highspeed is the fast serving tier of K3.1 Pro: the same model and context window, priced at ¥26 per 1M input and ¥136 per 1M output — exactly double the standard tier — with roughly 2–3x the throughput.

The trade

	Standard	Highspeed
Input /1M	¥13	¥26
Output /1M	¥68	¥136
Throughput	baseline	~2–3x
Cost per token	1x	2x
Cost per second of work	1x	~0.7–1.0x

The per-token price doubles while throughput rises 2–3x, so the cost of a fixed amount of work stays roughly flat and the cost of wall-clock time falls. Highspeed is therefore a latency purchase, not a throughput optimisation: it pays when a human is waiting, and does nothing for batch pipelines.

When it is worth it

• Interactive coding assistants and review tools where time-to-first-token is visible.
• Agent loops with many short calls, where per-call overhead dominates total latency.
• Anything with a service-level agreement measured in seconds.

It is not worth it for nightly batch jobs, evaluation runs or document processing — the standard tier produces the same output for half the token cost, and the queue does not care how fast each call returns.

What to verify

The multiplier is stated as “2–3x” rather than a fixed figure, so the effective cost per unit of work depends on your workload’s concurrency. At 2x throughput for 2x price, Highspeed is cost-neutral per unit of work and strictly better on latency; at 3x, it is also cheaper per unit of work. Measure on your own traffic before standardising on it.