GPT-6 Sol and Opus 5.5 low reasoning hit last-gen medium performance at 1/4 the cost, 4x faster

that_90s_guy · reddit · 2026-09-23

A Reddit post citing artificialanalysis.ai argues GPT-6 and Opus 5.5's biggest shift isn't raw performance but speed and cost: low-reasoning tiers nearly match last generation's medium-reasoning results at 1/4 the price and 4x the speed.

Key numbers: GPT-6 Sol (low) scores 34 on the Intelligence Index at $0.13/task in 27.75s (medium: 40, $0.25, 59.99s); Claude Opus 5.5 (low, fallback) hits 42 at $0.55/task in 81.35s (medium: 51, $1.34, 206.07s). Last-gen comparisons: GPT-5.6 Sol medium at 39/$0.50/125s and Claude Opus 5 medium at 45/$2.19/320.93s. Takeaway: frontier agent-level performance is now available at budget prices, a potential inflection point for running agents at scale.

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