DeepSeek DSpark Speculative Decoding Ported to Mac with Lossless Speedup

A-Rahim · reddit · 2026-07-07

Developers have ported DeepSeek's speculative decoding drafter, DSpark (built for DeepSeek-V4), to MLX, enabling native Mac execution alongside an OpenAI-compatible service and benchmarks. As an EAGLE-style drafter, the main model still verifies every drafted token, ensuring the output perfectly matches standard decoding (byte-for-byte identical in greedy mode, and verified exact sampling in temperature mode). It currently supports Qwen3 4B/8B/14B and Gemma-4 12B.

Benchmarked on an M4 Pro with 8-bit instruction targets, it achieves a 1.4–1.6x speedup for single users, and up to roughly 2x for code/math tasks using Gemma. The author notes that Mac speeds won't hit the commonly cited 2–4x figures, which the original paper never actually claimed.

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