Qwen3.8 125B (6B active) Flash-Next

User reports Qwen3.8-Flash-Next at 38.3 t/s generation and 857 t/s prefill on a Strix Halo 128GB. Setup is a ROCm llama.cpp branch with the BALANCED-2.1 GGUF quant (78.3 GB) and MTP speculative decoding, single card, 8K context. The 38.3 t/s is the short-answer figure at 8K; code writing reached 46.7 t/s and long prose 30.1 t/s at the same depth. Prefill fell from 857 t/s at 8K to 301 t/s at 256K, and generation from 38.3 to 25.2 t/s. GPU memory stayed at 68-70 GiB across the full window.