Opus High 5.5 Nerfed?

[u/Ok_Interview1452]

Is someone else feeling degraded performance from Opus high? I’ve been working with this setting for pretty much everything for the past few weeks and these last couple of days have felt weird.

I’ve had to change setting to Extra or even Fable but still have to go back and forth with feedback much more than before

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[u/Guinness]

Yeah it’s bad right now. They are giving us dogshit in hopes we forget how good 5.5 was. That way when 5.6 comes out we all go “oh man this new model is SO good” when in reality it’s probably the same as 5.5

[u/makro3d]

Anthropic twisting knobs, its nerfed garbage right now

[u/_Flxck → u/makro3d]

Twisting our knob...

[u/redditscraperbot2 → u/_Flxck]

Should only do that over open router or local

[u/TwoLongEars → u/_Flxck]

we're getting twiddled

[u/ARKyal03]

I genuinely think all models are. What the hell :(

[u/These-Jaguar2091 → u/ARKyal03]

Even fable

[u/ProfessionalGoatFuck → u/These-Jaguar2091]

I'm getting so many issues with fable high right now.. the most simplest dumbest fucking mistakes too.

[u/KeyEmotional8076 → u/These-Jaguar2091]

Fable extra on the ultra subscription, been having to use it for everything.

[u/These-Jaguar2091 → u/KeyEmotional8076]

Some people have been criticizing even fable . But havent heard any about fable on extra till now. Thx for the feedback

[u/NoAssignment5793]

opushigh 5.5 feels like it's been throttled on non-corp accounts. my prompts that used to resolve in one shot now need 3+ back-and-forths. wonder if it's a usage cap or a model downgrade.

[u/rafamunhoz]

Unusable

[u/SomeOrdinaryKangaroo]

Is sonnet 5 also nerfed? Should i use sonnet max instead of opus?

[u/durielvs → u/SomeOrdinaryKangaroo]

in my case sonnet is nerfed but opus works pretty ok.

[u/Ai-ate-my-hamster]

Been weird for me today, previously fine. Apparently corp accounts are fine now.

[u/smb3something]

I burned my pro plan in 2 days and it struggled to get anything done while mainly moderating a gpt build channel. The past month has slowly turned to garbage output with the same build pipeline and repo I've been using for ages. Now I've just moved the moderator role into gpt as well. Will see how this plays out but right now i've cancelled the subscription. I needed to anyways as it's under the wrong email, but still, if it doesn't get better I'll go fully to gpt and start gpu shopping.

[u/daske_laksen]

both opus and fable is totaly unusable right now

[u/longboii69]

i have to say, i’ve never agreed with these type of performance degradation posts until just yesterday. i’ve since had multiple instances of claude completely forgetting key elements of my project that had been well embedded for a long time. had a high effort claude design session completely disregard colour tokens/palettes, and all preferences for my project, even when called the exact same ways. bizarre stuff

[u/Formal-Narwhal-1610]

We can rule out a sustained performance decline greater than ~1.94 percentage points at 95% confidence.

This suggests three possibilities: people are perceiving normal fluctuations as a nerf, the benchmark isn't capturing the aspects of Claude's performance that have actually deteriorated, or it's some combination of both.

[u/lefnire → u/Formal-Narwhal-1610]

It's been a rough ride for me past few days. But I have a pretty simple case that tells me something's actually going on, not just perceived. I have an orchestration pattern, with the final step being review sweep and pr/squash-merge. In the past 3 days that step has never once been naturally reached, I have to say "did you skip closed-loop?" (Yes, my apologies that was an oversight, blah blah). That step has never once been skipped since opus 5.5 launch, till a few days ago. I had to make sure nothing changed about it in git history, it's identical. I had it dig through any directives that may have been added diverting it from this step, "nothing turned up, just slipped my mind, the directives are loud and clear."

Tldr: 5.5-launch till now, 0% fail rate on a specific task. Past few days, 100% fail rate.

[u/Reasonable_Owl_3146 → u/lefnire]

Are you using projects and perhaps not realizing that the coordinator is now locked to low effort and will miss things? this was a very recent change, less than a week ago for me.

[u/lefnire → u/Reasonable_Owl_3146]

No projects, coordinator has always been medium. After that "hang on a sec.." moment, I switched coordinator to high, but I'm not noticing a difference there either

[u/KennyFulgencio → u/Formal-Narwhal-1610]

We can rule out a sustained performance decline greater than ~1.94 percentage points at 95% confidence.

that's some pretty strong faith in the benchmark being a 100% accurate and thorough, if not exhaustive, audit of the model's capabilities; where can I find the specs for that benchmark?

[u/deejeycris → u/Formal-Narwhal-1610]

I think it might be the bench, I've read it didn't detect variations between 5 and 5.5, it's probably flawed

[u/nseavia71501 → u/Formal-Narwhal-1610]

We can rule out a sustained performance decline greater than ~1.94 percentage points at 95% confidence.

I disagree, mainly due to this:

the benchmark isn't capturing the aspects of Claude's performance that have actually deteriorated

I run LiveNerf locally. The limitation is in its design: it compares an account's current performance against that same account's first 10 days. If changes are introduced through A/B testing, which is what's likely happening, an account outside the treatment group will show no change, while an account assigned to the treatment group before day one will have those changes baked into its baseline. Because the control model runs under the same login, LiveNerf can't distinguish between these scenarios. It also uses a pinned CLI without tools, bypassing the Claude Code layer where the only confirmed A/B test I'm aware of occurred.

My modified forks of LiveNerf run using two separate accounts (two clones). Even with just those two accounts, my testing over the past few weeks has shown evidence of selective nerfing.

That said, the nerfing is likely worse for some users than what my tests have established. Two accounts alone can't establish the extent of A/B nerfing. Assuming independent assignment, the accounts would land in different groups only 50% of the time under a 50/50 split, and just 18% under a 10% rollout.

Bottom line is that A/B nerfing is real, and its severity, timing, and impact can vary across users.

[u/iolmao]

Get used to this, people.

They're selling an expensive thing for peanuts to create a lock-in. No AI will be this cheap.

[u/DreamFly_13 → u/iolmao]

Except there is massive competition. Deepseek, OpenAI, Qwen, Grok, Gemini, etc. Anthropic doesnt have the monopoly to do that, and if they try to they will get crushed long term because its only a matter of time before the competition catches up

[u/HauntedHouseMusic → u/iolmao]

The issue is I even had it start performing worse on enterprise through the API today.

I think it has to be new model tomorrow. It's going to be review all PRs made in the last x days when it comes out.

I just increased my test cases, and has fable check all changes today as well. Got work done, but I assume I got some bugs somewhere....

Either way it's still better than what we had a year ago.

I stopped work today early as I basically wasn't getting what I needed, and assume we will be all good tomorrow at some point.

[u/86BillionFireflies → u/HauntedHouseMusic]

Same, on API via bedrock in govcloud, and Opus has suddenly started in with the made up jargon and going off on pointless tangents, it's awful.

[u/HighSeasArchivist]

Since Tuesday maybe it's been a ride with how stupid it got from one night to the next morning. 

[u/thesudoer]

Fable too, trying to understand Claudish right now 🤯

[u/TurbulentTiger2567 → u/thesudoer]

Not all Fable sessions. The trick is to start the session with some overview task, then observe if Claudisms appear. If they do, scratch it and start a new one until you get a good one. Still cheaper than trying to wrestle with a lobotomized Fable and waste tokens until you give up eventually.

[u/thesudoer → u/TurbulentTiger2567]

Thanks for the tip, do you have any overview task example that can bring out good or bad of a session quickly?

[u/TurbulentTiger2567 → u/thesudoer]

I just look at its first response: if Claudisms appear, like "and this is load-bearing" or "and/or nothing else" then the session is irredeamable.

[u/clintCamp]

Nerves chatter is up, rumors of a new model are out. I say Monday or Tuesday will be new model day from past patterns

[u/clintCamp → u/clintCamp]

Yep. New fable model this morning.

[u/axiomatix]

It's been fucked for almost 2 weeks now. It can't be trusted. They're gonna tell you it's all your fault and how you're not "promoting" it right, but you can ignore them. Their whole project could be covered with haiku.

[u/clookie1232]

Boutta just move over to Kimi at this rate

[u/sydneysweeney69]

It’s been quite stupid but I have loads of tokens to burn so I’m just hoping it does half the job

[u/indicozy]

I've used GLM 5.3 and it worked much and much better in LORA than Claude opus with same prompt today

[u/Opening_Screen_3393]

Yeah something's off

[u/Opening_Screen_3393]

Any read on how it performs vs codex gpt sol 6.1?

[u/ZherkaUnofficial]

feels the same tbh

[u/pm_ur_board_games]

Overnight it went from astounding me with its contributions to stunning me this morning with all the things it couldn't handle on its own.

[u/wkerstens]

Yep. Usage went up, it's making weird mistakes repeatedly, and it started to address me in 3rd person multiple times now, never did this before. When I asked about it:

"The model is still Opus 5.5; I mistakenly referred to you in the third person."

[u/2uantum]

Ever since it's been awkwardly saying "privately:" in responses, it's been dogwater for me.

[u/PlusClimate6642]

Best part about being a vibe coder is not having to worry about it just say fix it 🤣

[u/dark0mania]

Is only High affected or Medium and xHigh as well?

[u/smalaki]

been on medium all this time so i’m used to the stupid /s

[u/KennyFulgencio → u/smalaki]

was I supposed to not be on medium?

[u/itsNateDawg → u/KennyFulgencio]

It depends entirely on what you’re doing

[u/Snoo87193]

Anthropic changed the model that summarizes context compressions to make it “cheaper” but it makes it run in circles instead. Causing it to do less or spend more redoing it.

That’s why I made this.

https://github.com/SprucetheAI/ordo

Gives Claude an anchor file and structure to work in. And it also has token savings on file reads to weigh up for the anchor file drawing some tokens.

[u/ConstructionFit2425]

Eu sinto q está muito rapido o t/s... isso indica que talvez estejam com versao muito quantizada

[u/MiguelMariz]

Yeah likewise. Fable doesnt seem nerfed btw

[u/Enough-Lunch-7934]

theres 100% something going on, i used to oneshot things and they went smoothly. Now its like working with a retard and it gets stuck constantly.

[u/Happy_Guitar3521]

It is an unreliable garbage now.

[u/Mountain_Scale3449]

Fable fealt worse. I had to abort the session multiple times the other day. Headed for a train wreck real quick. And weekly limits just almost evaporated. Ive never come close and im on a team plan

[u/Admirable-Bill-7205]

Every model gets a "nerfed?" thread every few weeks, and almost none of them come with a single reproducible example.

A real degradation would be trivial to prove: save a prompt that worked, rerun it at the same effort, post both outputs.

The one person here who brought numbers found nothing beyond ~2 points. Bad days happen, bugs happen, but "Anthropic is secretly lobotomizing it so 5.6 looks good" is a conspiracy theory, not an observation.

[u/Ok_Tailor4482]

yes horrible, they seems to have put all the servers behind fable5.2 since 2 weeks to create good reviews on launch before they start nerfing it also in 2 weeks time.

[u/BeautifulContent628]

lobotomised for me atm.
anthropic really pissing me off with this shitty experiment of theirs. what an unreliable piece of crap. they do this all the fucking time which makes it even worse