Agent harnesses drive significant prefill overhead and energy consumption
October 16, 2026
Harness-induced cache misses can increase request energy use by 2x and prefill work by 2.7x. In deep sessions exceeding 128k tokens, a single turn re-reading half its prompt can cost as much as 600 normal turns due to recomputation from the first point of divergence.
HOW THIS AFFECTS YOU
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builderYou must optimize how your agent harness modifies prompts to prevent expensive cache breaks.
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founderInefficient harness design directly scales your GPU compute costs and energy footprint.