Zhipu, the Chinese company behind the open-source GLM model family, appears to be gray-testing a new speed-focused model. Users have spotted an unannounced GLM-5.3 Highspeed inside ZCode, Z.ai's coding client, and a screenshot posted on X shows it generating at 490 tokens per second — just shy of 500. Zhipu has made no official announcement.

That framing matters. This is a leak-and-listing story, not a launch, and what follows draws on a user-posted screenshot, a third-party catalog listing, a month of Reddit detective work, and an official support answer. An official announcement or an API listing would change the story; neither exists yet.

How fast is 490 tokens per second

TPS counts the tokens a model generates each second. At 490 TPS, the generation stage of a 10,000-token output takes roughly 20 seconds — a full agent reply that finishes about as fast as you can skim it. Thinking time is separate and comes first; the 20 seconds is pure output.

For scale: GLM-5.3-FlashX, released by Zhipu just last month, peaks at 200 tokens/s, and Artificial Analysis measured GLM-5.3-Flash on the Z.ai API at about 60 tokens/s of output. The two numbers measure different models under different conditions, so the ratios are approximate. If the screenshot holds up, the gray-test model runs at more than double FlashX's peak and roughly eight times Flash's measured output.

What the catalog listing says

The model was listed in Pi's catalog before it was spotted in ZCode. The entry — glm-5.3-highspeed under the zai provider — shows a 1,000,000-token context window, 131,072 max output tokens (about 128K), and reasoning-effort settings of low, high, and max. That is identical to the standard GLM-5.3 on every listed axis; only the speed differs. On paper, it reads like a throughput-tuned serving variant rather than a new generation. Pi currently lists every rate for the model at $0, which says more about an unreleased listing than about real pricing.

The Pi catalog entry: same numbers as the base model, a different name.
Pi model catalog page listing glm-5.3-highspeed under the zai provider

The Omen Alpha theory

Reddit connected the dots weeks before the screenshot. A thread on r/ZaiGLM, about 28 days old, links the model to "Omen Alpha", an anonymous model that has been live in OpenCode's testing ground since September. Inside OpenCode, its identifier resolves to zhipu/omen-alpha, and reports in the thread call it "almost identical to 5.3 flash but 3 times the amount of tk/s."

The thread's most memorable test involved the classic "pelican riding a bicycle" generation prompt. The output clip featured a duck pedaling a bicycle. Wrong bird, right bicycle — delivered very fast.

The identity of Omen Alpha is still disputed. Guesses include GLM-5.3 Highspeed itself, GLM-5.3-Omni, and GLM-5.4-Flash.

r/ZaiGLM commenters on Omen Alpha's speed and identity.
Reddit comments discussing Omen Alpha as a stealth GLM model in OpenCode's testing ground

Zhipu's speed track record

Zhipu has run this play before. In May, the company shipped GLM-5.1 Highspeed at 400 tokens/s — then the fastest output speed among major model providers' APIs. If the new model truly sustains 490 TPS, it tops Zhipu's own record, and long agent runs get much faster to sit through. The wait shifts back to how long the model thinks, not how long it types.

Availability: a randomized gray release

Per an Ask ZCode answer citing the changelog, GLM HighSpeed is a randomized subscription-side perk. After the update, the system grants the accelerated experience to a subset of subscribers, unpicked users are unaffected, and both the selection status and the entry point are shown inside the client. Whether you have the model at all depends on which side of the random draw your account landed.

The community verdict so far fits in one line: fast, thinks for a long time, and the output quality holds up.

Ask ZCode's official answer on the randomized HighSpeed perk.
Ask ZCode official answer explaining the randomized GLM HighSpeed subscriber perk

Sources