Qwen3.8 27B

User reports approximately 15 tokens/s generation speed running Qwen3.8-27B on a DGX Spark (GB10) with llama.cpp. Setup is llama.cpp with UD-Q4_K_XL GGUF quant and q8_0 KV cache, using MTP speculative decoding with draft-mtp and spec-draft-n-max 2, batch 4096, ubatch 2048, flash attention on, 99 GPU layers, 8 threads. User notes that NVIDIA forum users reported similar performance with vLLM, but an official SGLang post reported 38 tokens/s decode throughput on DGX Spark, and asks whether a configuration or optimization is missing or whether the model/platform is not yet fully optimized in llama.cpp.