Short answer
Zhipu’s Open Platform documentation identifies GLM-5.1-HighSpeed as a faster version of GLM-5.1 and gives the API model ID glm-5.1-highspeed. The documentation excerpt available for this guide reports 400 tokens per second and says access is limited to some enterprise customers. Treat that speed as a provider-reported claim—not a guaranteed rate for every request or workload. (Zhipu model documentation)
What is established—and what still needs confirmation
| Detail | What the available source material supports |
|---|---|
| Product name | Zhipu documentation identifies GLM-5.1-HighSpeed as a faster GLM-5.1 version. |
| API model ID | glm-5.1-highspeed |
| Access | The documentation says access is limited to some Zhipu Open Platform enterprise customers. Confirm eligibility for your account. |
| Endpoint and authentication | The documented example identifies https://open.bigmodel.cn/api/paas/v4/chat/completions and bearer-key authentication. |
| Context and output limits | The exact HighSpeed-specific specification rows are not substantiated by the excerpts available for this guide. Confirm limits and any conditions in the current model documentation before designing around them. |
| Modalities and listed features | Text input/output and support for thinking modes, streaming, function calling, context caching, structured output, and MCP are not confirmed by the exact excerpts available here. Check the current model documentation for each feature you plan to use. |
| Request parameters | The available excerpt supports the endpoint, bearer authentication, and model ID; it does not establish the accepted request fields or their behavior. Check the model-specific example before relying on parameters such as stream or max_tokens. |
The linked model page may contain additional specifications. The qualifications above distinguish those unconfirmed details from the endpoint, authentication, and model ID supported by the available documentation excerpt. (Zhipu model documentation)
What does “400 tokens/s” mean?
Zhipu reports output speed of 400 tokens/s. The source material available here does not include benchmark conditions such as workload, hardware, concurrency, prompt and output lengths, measurement procedure, or latency percentiles. The figure therefore does not establish typical performance for your application or guarantee a particular response time. (Zhipu model documentation)
A repost dated May 22, 2026, attributed to Zhipu, also describes the capability as “400 TPS” and claims it is stable in production rather than a peak figure. The repost does not provide supporting measurements, and it does not define whether “TPS” means the same thing as “tokens/s.” Treat that stability statement as an attributed product claim, not an independently established result. (May 22, 2026 repost)
Output throughput is not the same as end-to-end response time. A user’s wait can also include time to first token, network delay, queueing, input processing, reasoning, tool calls, and the time needed to generate the complete answer. A high output-token rate may be relevant for long streamed responses, but alone it does not establish that requests will start quickly or finish within a particular time.
The May 22 repost attributes speed improvements to inference-engine, scheduling, and infrastructure work; it specifically mentions dynamic batching, request merging, and KV-cache scheduling. These are the repost’s descriptions of the system, not independent evidence of performance under your traffic pattern. (May 22, 2026 repost)
Is it worth evaluating for your workload?
It is a candidate to test if latency materially affects your product experience and your organization can obtain access. The repost names coding, real-time interaction, business decision support, and real-time voice-related workflows as intended scenarios. Those use cases do not by themselves prove application quality or establish audio input/output support in the API. Verify the specific interface capabilities your implementation requires. (May 22, 2026 repost)
A practical selection rule:
- Evaluate HighSpeed when faster generation could improve a user-facing interaction or shorten a multi-call agent workflow.
- Compare it with standard GLM-5.1 when task quality matters as much as speed. The repost says the high-speed version retains GLM-5.1 capabilities, but the supplied text does not include reproducible side-by-side results.
- Do not select it on the 400 tokens/s figure alone if your service depends on predictable first-token latency, sustained concurrency, strict service levels, or a specific cost ceiling. Measure those under your workload and confirm the commercial terms.
A practical evaluation plan
This is a suggested test plan, not a test result:
- Choose representative prompts, including typical and longest inputs. Keep prompts and tool configuration identical for HighSpeed and standard GLM-5.1.
- Test at the concurrency levels you expect in production. Record time to first token, total completion time, output tokens per second, errors, and timeouts.
- Score output quality against task-specific criteria—for example, whether a code change passes your existing tests or a structured response validates against your schema.
- Compare billed usage and access terms for each option. Repeat requests to observe variability instead of relying on one response.
For an agent, measure the full task as well as individual calls: lower per-call latency only helps if quality and tool-use behavior remain adequate across the workflow.
Calling the API
The available Zhipu documentation excerpt identifies a chat-completions endpoint, bearer-key authentication, and the model ID. Confirm the accepted request body and parameter behavior in the current model-specific example before implementation. In particular, the excerpts available for this guide do not establish support or behavior for stream or max_tokens. (Zhipu model documentation)
- Endpoint:
https://open.bigmodel.cn/api/paas/v4/chat/completions - Authentication:
Authorization: Bearer YOUR_API_KEY - Model ID:
glm-5.1-highspeed
Pricing: don’t substitute the standard-model rate
The Zhipu pricing excerpt available for this guide lists standard GLM-5.1, not GLM-5.1-HighSpeed. It states prices in Chinese yuan per million tokens: for standard GLM-5.1, input is ¥6 and output ¥24 when input length is under 32K; for input length of 32K or more, input is ¥8 and output ¥28. It also lists cache-related charges. These are not confirmed HighSpeed prices and should not be used to estimate a HighSpeed bill. (Zhipu API pricing)
Before production adoption, confirm the HighSpeed model’s input, output, and cached-token rates; any minimum commitment or quota; and whether billing varies by context length. Also confirm account eligibility and applicable service terms. Until then, a cost comparison with standard GLM-5.1 remains unresolved.
Bottom line
Zhipu’s Open Platform documentation identifies GLM-5.1-HighSpeed and its API model ID, and reports 400 tokens/s. The available excerpts also identify the endpoint, bearer authentication, and restricted enterprise access. They do not substantiate the exact context/output limits, modalities, feature list, or request-parameter behavior presented elsewhere as specifications, nor do they establish HighSpeed pricing. Confirm those details for your account, then test latency, quality, reliability, and cost on a matched workload. The headline speed is a reason to evaluate the model—not a substitute for those checks.
Sources
GLM-5.1-HighSpeed — Zhipu AI Open Platform Documentation