OpenRouter Fusion asks a panel of models, then a judge picks — 7x slower, 4x the cost (openrouter.ai)
An engineer's quick eval put it plainly: about 7x slower and 4x the cost of calling one frontier model directly, which lands Fusion in a 'use it only when you really need it' bucket.
The deeper objection came from someone who shipped this exact thing months ago: asking one model to judge another mostly measures how closely the answer resembles what the judge would have said. It's temperature, dressed up as a panel.
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