Dense-to-MoE conversion: +32% GPU speed but perplexity degrades ~40%

Bayliner1980 · reddit · 2026-10-13

An update on converting dense models to MoE: bayliner1980 released Qwen2.5-1.5B-MoE-A0.9B plus GGUF versions of both 0.5B and 1.5B conversions.

Results: WikiText-2 perplexity rises 41% (10.41→14.63), zero-shot mean accuracy drops 0.565→0.462 with ARC hit hardest; but generation speed gains +32% on GPU (RTX 4060) and +41% on CPU — the first conversion clearly faster than dense even on GPU. Honest caveat: at this size quality matches the faster Qwen2.5-0.5B, so it's a proof of concept; the approach should pay off more on larger models where MLP dominates compute. GGUF is larger than dense due to untied output head in llama.cpp MoE.

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