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Arena.ai analyzed more than 26,000 Agent Arena sessions between September 12 and October 23, 2026, covering 30 agents and 13 labs. Its conclusion states that if all cached tokens were billed at the model's full input price, the cost of tasks sent to its top ten agents would become 3.6 times higher, i.e., 260% more; a typical Claude Fable 5.1 task currently costs $7.44, versus $27 without caching. In the sample, a single cache miss would increase a typical task's bill by 5%. There have been no further developments as of yet.
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Arena analyzes 26,000 Agent sessions: costs are 260% higher without cachingDevelopments
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Oct 30
Arena
Arena analyzes 26,000 Agent sessions: costs are 260% higher without caching
Arena.ai analyzed more than 26,000 Agent Arena sessions between September 12 and October 23, 2026, covering 30 agents and 13 labs. If all cached tokens were billed at the model's full input price, the cost of tasks sent to its top ten agents would become 3.6 times higher (260% higher); a typical Claude Fable 5.1 task currently costs $7.44, versus $27 without caching. In the sample, a single cache miss increases a typical task's bill by 5%.
Arena
Arena analyzes 26,225 Agent sessions: without caching, agent costs are 3.6 times higher
Arena analyzed 26,225 Agent sessions, 30 agents, and 13 labs from September 12 to October 23, 2026, and found that if billed at the full input price, the typical task cost for the top ten agents would be 3.6 times higher, and 592% higher on MiMo V2.6 Pro. For agents, 86% to 96% of tokens are repeatedly read context, while their own output accounts for only 1% to 2%. Cache invalidation increases the typical task cost by about 5%, and on Claude Fable 5.1, 1 in every 10 sessions sees an increase of more than 18%.