KV Cache Gap of 39x: Four Open-Weight Agent Flagships Compared
Four open-weight flagships compared: MiniMax M3.1 Flash (428B/23B active), DeepSeek V4.1 Flash 1017, GLM-5.3, and Kimi K3 - all four appear in MiniMax's official model-card comparison table, so calibers align naturally, with two caveats stated upfront: the whole table was run by MiniMax alone (the card admits it), and each benchmark used a different harness (Terminal-Bench 4.0 on Codex 0.149.1, DeepSWE on mini-SWE-agent at 512K, CyberGym on Claude Code); every M3.1 Flash score is vendor-reported with no third-party replication. The only third-party ruler is the AA Intelligence Index: DeepSeek 1017 at 45, M3.1 Flash 42, M3 at 29 (GLM-5.3's 59 is a different index in a different month, directional only). The real efficiency gap sits in KV cache: DeepSeek 1017 officially uses 890 bytes per token against M3.1 Flash's 34,560 (vLLM engineering figure) - a roughly 39x memory difference for self-hosted long context. There is no official M3-to-M3.1 benchmark table, only three claims (near-3x speed, 200+ tok/s, 70 percent lower agentic cost with no published method), a price cut (0.30/1.20 to 0.15/0.60 dollars), and vLLM engineering data (weights 451.5 to 250.1GB, KV 61,440 to 34,560 bytes per token). Price panorama: M3.1 Flash at 0.15/0.60 dollars with 0.015 cache; DeepSeek matches off-peak but charges 0.003 cache and doubles at peak; GLM-5.3 at 8/28 yuan with 2 cache; K3.1 Pro at 2/10 dollars (media-cited screenshot). The Kimi trap: K3's 12.6 on TB4.0 versus K3.1 Pro's self-reported 65.7 shipped early October 24 differ in version and harness, and K3.1 Pro weights only land before November 4. Contradictions listed without adjudication: Automation-Bench 62.2 versus 62.8, 428B versus 220B HF metadata, checkpoint sizes 250.1/233/220GB.