tl;dr Mamba-3 is a new state space model (SSM) designed with inference efficiency as the primary goal — a departure from Mamba-2, which optimized for training speed. The key upgrades are a more expressive recurrence formula, complex-valued state tracking, and a MIMO (multi-input, multi-output) variant that boosts accuracy without slowing down decoding. The result: Mamba-3 SISO beats Mamba-2, Gated DeltaNet, and even Llama-3.2-1B (Transformer) on prefill+decode latency across all sequence lengths at the 1.5B scale. The team also open-sourced the kernels, built using a mix of Triton, TileLang, and CuTe DSL for maximum hardware performance. This blog is cross-posted on the Goomba Lab blog and covers work done in collaboration between researchers at Carnegie Mellon University, Princeton University, Cartesia AI, and Together AI. Since the release of Mamba-2 in mid-2024, most architectures have switched from Mamba-1. Why? Mamba-2 made the bet that training efficiency was the largest bottleneck for state space models (SSMs), and thus simplified the underlying SSM mechanism to deliver 2−8× faster training compared to its predecessor, leading to wider adoption. …