RTX 3090 runs 27B LLM 4.6x faster via pure inference optimizations, no new hardware

rickasaurus · x · 2026-10-19

A r/LocalLLaMA user pushed a 2020 RTX 3090 running Qwen3.8 27B from 82 to 382 tok/s on a document-quoting task (4.6x) using only software tuning: MTP tweaks, a DFlash2 drafter plus a lookup drafter, and 16-token verify steps. Normal chat runs at 133 tok/s (still 1.6x faster) with context extended to 138K.

The poster reports similar gains on his own 4x 3090 rig: DeepSeek V4 got 29x faster, Flash prefill went from 433 to 1906 tok/s in one day, and a MiniMax H3 clip dropped from 11:21 to 3:45 — the GPUs had been idle-waiting 92% of the time. Core claim: local AI performance is a software problem, not a hardware problem.

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