/Tech7h ago

Superconductor developer Sergey Karayev says Fable 5 resolved a SwiftUI memory leak that GPT-5.5 missed, costing $40

The successful optimization run took two hours to execute.

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Sergey Karayev@sergeykarayev#1421inTech

@mitchellh We found Fable to be the only model that found a cause of a front-end memory leak

Sergey Karayev@sergeykarayev

Good stuff: we launched Fable 5 on a real memory leak ticket alongside GPT-5.5 and Opus 4.8 (a total of 5 agents in one click).

Fable was the ONLY ONE that found the root cause: an event listener dependency holding refs to replaced DOM nodes.

Red before. Green after. Hell yeah.

9:50 AM · Jun 11, 2026 · 1.8K Views
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Some users praised Fable AI's deep code optimization and suggested launching agents sequentially to address token costs.

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Bindu Reddy@bindureddy

Cost per successful task is the only metric in AI that will matter!

On every day tasks, GPT 5.5 is as successful as Fable and is about 30% cheaper!

AI becomes ubiquitious as the cost goes down!

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@sergeykarayev I believe it. But that doesn't mean you should run it against every bug. You should run the cheaper models first, which will probably find it, then fallback to it.

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Sergey Karayev@sergeykarayev

@mitchellh Interesting feature idea: launch agents one at a time. We tend to not be token-cost-conscious so we just launch all at once, but it's a very good idea.

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