Youssofal/Qwen3.8-27B-MTPLX-Optimized-Speed

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Qwen 3.8 27B Optimized Speed

4-bit dynamic quant. Great coding speeds and good quality. Recommended.

This is the model MTPLX recommends for coding on a modern Mac with 32 GB or more. It is Qwen3.8-27B with its native multi-token-prediction head kept, so MTPLX can draft several tokens ahead and verify them in one pass. Same model, same output distribution, a lot more tokens per second.

Speeds

Measured on an M5 Max, fans verified at max, single stream, generation running to the model's own stop, official Qwen 3.8 sampling (temperature 1.0, top-p 0.95, top-k 20).

Run	tok/s
Coding task, medium reasoning, mtplx serve	58.7
Same task inside the MTPLX Mac app	55.5
Long reasoning at xhigh, 28k and 20k token answers	35.1 and 37.3

For context on the same night and the same task: the previous MTPLX flagship, Qwen 3.6 27B Optimized Speed V2, ran 59.9 to 60.1 tok/s, and oMLX 0.5.7 with its own Qwen 3.8 4-bit MTP quant ran 63.3 tok/s. MTPLX Bare Speed ran 65.2 on that task; this build gives up a few tok/s to be much closer to the original model.

Draft acceptance on the coding task by depth: 0.95, 0.88, 0.80. Verify cost 50 to 53 ms per round.

How it is built

A dynamic 4-bit quant, the same hand-tuned layout as our Qwen 3.6 Optimized Speed V2:

• The bulk of the model is 4-bit with 32-weight groups.
• The parts that hurt most at 4-bit are kept at 8-bit: the embeddings, the output head, all 48 GDN output projections, and the last 8 MLP blocks.
• Sensitive parts stay 16-bit: the GDN convolution kernels and recurrent state parameters, every norm, and the whole MTP head.
• KL divergence to the original bf16 model on our coding battery: 0.0220. That is 1.7x closer to the original than the flat 4-bit Bare Speed build.

Download	20.4 GB
Peak unified memory (measured, this artifact)	23.6 GB
Context window	262,144 tokens
MTP depth	3
Sampling	temperature 1.0, top-p 0.95, top-k 20 (the official Qwen 3.8 contract)

The tuned depth and draft settings ship inside mtplx_runtime.json. MTPLX reads them on load. No flags needed. Reasoning effort levels (xhigh, medium, low) work, and preserved thinking flows through the MTP path like any other tokens.

Speculation in MTPLX is exact. Drafts are accepted with the probability-ratio rule plus residual resampling, so what you sample is what the model would have sampled without speculation, at any temperature.

Use it

Mac app: download at mtplx.com, pick "Qwen 3.8 27B Optimized Speed". It is the default on modern Macs.

Command line:

pip install mtplx
mtplx serve --model Youssofal/Qwen3.8-27B-MTPLX-Optimized-Speed

Then point OpenCode, Pi, Claude Code, Cline, or anything that speaks the OpenAI or Anthropic API at http://127.0.0.1:8000.

Siblings: Bare Speed (quickest burst chat speeds, lower quality) and Optimized Quality (8-bit, perfect quality). On an M1 or M2 Mac use the FP16 build of this model.