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Qwen3.5 inference speeds spark LocalLLaMA debate
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REDDIT · REDDIT// 32d agoINFRASTRUCTURE

Qwen3.5 inference speeds spark LocalLLaMA debate

A LocalLLaMA thread asks why Qwen3.5-9B(p1) can run nearly as slowly as Qwen3.5-35B-A3B(p2) on consumer AMD hardware. The replies point to a bad apples-to-apples comparison: much longer prompt length, different context pressure, dense-vs-sparse activation behavior, and likely VRAM spillover.

// ANALYSIS

This is a good reminder that local LLM speed is usually a systems problem before it is a model-size problem.

  • The key reply notes the 9B run used a roughly 4.7k-token prompt versus about 1.6k for the 35B-A3B run, which can heavily distort throughput comparisons
  • The “A3B” suffix matters because the 35B mixture-of-experts variant only activates about 3B parameters, so a bigger headline size does not automatically mean slower inference
  • Community suggestions point to memory fit as the real bottleneck: once weights or KV cache spill beyond VRAM, a smaller dense model can feel unexpectedly sluggish
  • The thread also surfaces practical tuning advice for local serving stacks, including AWQ quantization, vLLM, and enabling MTP where supported
// TAGS
qwen3-5llminferencegpuopen-weights

DISCOVERED

32d ago

2026-03-11

PUBLISHED

32d ago

2026-03-11

RELEVANCE

7/ 10

AUTHOR

BitOk4326