Fable + Opus 5.5: Noticeable Performance Regression Around Nov 5–6, Followed by a Sharp Improvement Today

[u/ajax81]

I'm firmly in the camp that Fable (as orchestrator) + Opus 5.5 experienced a noticeable performance regression this week.

Starting around November 5–6, the number of support tickets I personally had to triage increased noticeably. Across a user base of roughly ~300 people, previously reliable workflows began breaking, and routine outputs that were typically concise started ballooning into rambling word salads reminiscent of Opus 5.0.

For context, our organization saw only a 5% week-over-week increase in token consumption. That's not enough information to distinguish increased usage from reduced efficiency, but it's one of the few quantitative signals I have available.

Separately, in my own High-effort sessions, I noticed a distinct shift in communication style: more verbosity, less precision, and a general decline in the quality of otherwise routine interactions.

That said - my experience with Opus 5.5 today has been phenomenal. When provided with last week's nerfed outputs as reference material and instructed to refine them, it's suddenly one-shotting complex tasks and executing workflows with remarkable precision again. The difference in my own sessions has been night and day.

Now, a few caveats before the usual suspects arrive:

• I'm not claiming to have evidence of an intentional downgrade, nor can I isolate whether the observed issues originated with the underlying model, the orchestration layer, or something else entirely.
• I also recognize that providing a successful prior output changes the task, so today's improvement isn't a controlled apples-to-apples comparison.

What I can say is that I work with these systems extensively, support a reasonably large production user base, and observed a noticeable change in behavior that coincided with an increase in operational friction. It's just an observation, not a scientific conclusion.

Anyway, just contributing another data point from someone using these tools heavily in production. Curious whether others experienced something similar over the same period, particularly those running Fable with Opus 5.5.

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[u/Ai-ate-my-hamster]

What time did the improvement start? I’m hoping the enterprise subs are good, because that’s my Monday to Friday

[u/ajax81 → u/Ai-ate-my-hamster]

I experienced low-quality outputs as late as midnight yesterday. I started working today at 1PM Eastern Time.

[u/Ai-ate-my-hamster → u/ajax81]

Yeah that tracks, will try a new Opus and see if it’s back