DeepSeek V4.1 Flash 552B (16B active)

User reports DeepSeek-V4.1-Flash at 37.95 tok/s single-stream decode across 8 categories and 902 tok/s cold prefill at 2K tokens on four DGX Sparks. Setup is vLLM TP4 across four DGX Sparks over ConnectX-7 RoCE, MXFP4 experts and MXFP8 dense weights, DSpark speculative decoding with k=5, the whole model in unified memory (56.6-68.9 GiB per Spark), 300K context window. Per category the single-stream decode was code 73.8 tok/s, JSON 52.1, math 50.9 and prose 24.4. Six streams reached 131.86 tok/s aggregate. Cold prefill was 1,539 tok/s at 32K and 1,194 at 64K.