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

User reports Qwen3.8-Flash-Next at 125 t/s generation and 5,879 t/s prefill on an RTX 5090 with the Infernix engine. Setup uses NVIDIA's NVFP4 quant with expert streaming from system RAM and SSD, n-gram drafting, and PCIe Gen5 x8. The engine is an offshoot of NInfer. Compared to Strata running Unsloth's UD-Q4_K_XL quant, Infernix shows 82% lower average time to first token (5.9 s vs 32.9 s) and 65% lower workload wall time (7.8 min vs 22.3 min). At concurrency=2, output reaches 143 t/s. The user notes the model is broadly on-par quality-wise with the Unsloth quant and that PCIe Gen5 x16 may yield higher performance.