MTP Performance Varies: 1.95x Boost on 3090, Hardware Matters for Decoding

In my MTP post, speculative decoding roughly doubled Qwen3.6-27B generation on a 3090. It's tempting to read that as "turn on MTP, go faster." So I measured it on a different model — Gemma 4 12B QAT — and it's a big win on my 3090. But the same model with the same MTP draft runs slower on an M1 Max.