# @witcheer — 2026-09-10

♥44 ↻0 · https://x.com/witcheer/status/2097921422005879100

I measured the six llama-server flags everyone argues about, on a 16k prompt, on six models:

RTX 5090, Qwen3.8-27B, Gemma 4 31B, Qwen3.6-35B-A3B, Nemotron Lightning, Ornith 35B, Qwopus Flash.

→ --flash-attn on: changes nothing. auto already picks it.

→ --parallel 1: free. +10% decode at depth on Gemma, 2.3 GB back.

→ KV cache q8_0: a memory lever on dense models only (1 to 2.6 GB). on a 3B-active MoE it saves 0.1 GB and still costs 5 to 7%.

→ KV cache q4_0: the tax. -17%, -23%, -27%, -23%, -29%, -17% decode against a 16k context, six for six. quality did not move: a full 198-item GPQA run on Ornith put f16, q8 and q4 KV at 100, 100 and 98.

→ MTP draft head: 2.2x on Qwen3.8 (embedded head), 1.5x on Gemma (community head), 0.7x on Lightning. above ~300 tok/s the verification pass costs more than it saves.

the first token on a 16k prompt: 5 to 6 s cold, 0.1 to 0.4 s once cached.

![photo](../../../media/HR1PwqJWUAwThu7.jpg)
tags: author:witcheer, has-image, kind:image, kind:tweet, on:qwen-3-8-27b, year:2026
cited on: _dossiers/qwen-3-8-27b.md, qwen-3-8-27b