GPT-5.6 Sol and Terra are far more efficient, but Codex is the bottleneck

haider1 · x · 2026-07-27

The post argues that Fable 5 and Opus 5 are good, but GPT-5.6 Sol and Terra are much more efficient.

It says the main bottleneck is not the models themselves but the harness around them — specifically Codex — and claims Anthropic’s edge comes from its harness and UX rather than raw model efficiency.

Related event: GPT-5.6 Leads in Efficiency Across Multi-Model Benchmark(2 posts)→

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