Gemma 4 26B (4B active)

User reports a ~3.8x generation speed regression on Apple M4 Mac Mini (16 GB unified memory) with Gemma 4 26B A4B IQ4_XS. Master build (d12cc3d) achieves 8.14 tok/s versus 27.18 tok/s on tag b8680, both built from source with llama-server and identical flags. Setup uses Metal backend, --flash-attn on, q4_0 KV cache, 65536 context, and -ngl 99. The regression is reproducible and not explained by memory or swap pressure; prefill on b8680 was 55.7 tok/s.