> The acceleration in late 2025 was likely influenced by non-AI factors. We investigated a variety of factors which could have contributed to the observed acceleration in late 2025, but details of many of these factors have been redacted.
Of note, "the acceleration in late 2025" believe has to do with Opus 4.5 which in my view and from Metr's analysis[0], was the point where their tests stopped working because the model was so good that doing work without using it took much more time.
> We guess that a majority (perhaps ≈80%) of the current (October 2026) acceleration is due to AI.... We believe AI’s contribution has grown relatively more important over time, and do not think the other factors we investigated would explain the sustained acceleration. The evidence of speedup from the usage of AI we describe below also seems compatible with a large contribution.
In a mini bet, I'd say that Anthropic is going to win by a large margin in what's going on. I've used the other models and no matter what the benchmarks are, places like OpenAI, Gemini, or the Deepseek / Kimi models haven't come close to the ability of the Claude models and harness. If what they say in this post is right, with "We did not identify any convincing bottlenecks to continued rapid progress.", this could be a sort of game over for the other models.
Even with Opus 5.5 in the past month and a half has been a changer in its abilities. In my dev process, I can give it much more freedom and trust with the workflows and connections I have to do the valid work to where I can do more, bigger tasks at once. I can't tell you how curious I am with the Opus 5.6 and whatever Model 4 is going to be called (along with the cost!) will do for dev work. And if this keeps increasing, and if there are subtle tricks that Anthropic has that the other companies don't, what that means for finding solutions and overall value and if the others are ever going to be able to catch up in any way.
All speculation, but what a time to be a dev in these times and get the first hand experience of all of this!
Maybe related to them potentially releasing a new model soon, but in the past week I've spent about 30% of what i've spent in the last month in the last week alone undoing what Opus 5.5 has started doing; it's barely usable at this point.
It lies, ignores instructions, actively invents requirements, and silently breaks parts of my codebase it morally disagrees with and then refuses to fix it. I'm pretty much ready to switch to open source models exclusively once the next generation comes around and they're at previous fable/astra performance.
I'm sick and tired of the bait-and-switch. It's also pretty clear to me that whenever I work on anything even tangentially related to Anthropic's business (I'm looking at you, agent harnesses or storing chat transcripts), it actively deteriorates in quality to the point where I'm left nearly weeping in frustration.
Can't wait for the future in which our corporate overlords pay Anthropic and AI not to advertise, but to silently break and degrade service for people building competing products.
Although unsurprising given that there’s perhaps a trillion dollars at stake, it is disappointing that this article opens with “Anthropic’s redacted the best parts”. The table of shared/redacted sources is unfortunately dominated by no/partly.
> The acceleration in late 2025 was likely influenced by non-AI factors. We investigated a variety of factors which could have contributed to the observed acceleration in late 2025, but details of many of these factors have been redacted.
Of note, "the acceleration in late 2025" believe has to do with Opus 4.5 which in my view and from Metr's analysis[0], was the point where their tests stopped working because the model was so good that doing work without using it took much more time.
> We guess that a majority (perhaps ≈80%) of the current (October 2026) acceleration is due to AI.... We believe AI’s contribution has grown relatively more important over time, and do not think the other factors we investigated would explain the sustained acceleration. The evidence of speedup from the usage of AI we describe below also seems compatible with a large contribution.
In a mini bet, I'd say that Anthropic is going to win by a large margin in what's going on. I've used the other models and no matter what the benchmarks are, places like OpenAI, Gemini, or the Deepseek / Kimi models haven't come close to the ability of the Claude models and harness. If what they say in this post is right, with "We did not identify any convincing bottlenecks to continued rapid progress.", this could be a sort of game over for the other models.
Even with Opus 5.5 in the past month and a half has been a changer in its abilities. In my dev process, I can give it much more freedom and trust with the workflows and connections I have to do the valid work to where I can do more, bigger tasks at once. I can't tell you how curious I am with the Opus 5.6 and whatever Model 4 is going to be called (along with the cost!) will do for dev work. And if this keeps increasing, and if there are subtle tricks that Anthropic has that the other companies don't, what that means for finding solutions and overall value and if the others are ever going to be able to catch up in any way.
All speculation, but what a time to be a dev in these times and get the first hand experience of all of this!
[0] https://metr.org/blog/2026-02-24-uplift-update/#wider-adopti...
Maybe related to them potentially releasing a new model soon, but in the past week I've spent about 30% of what i've spent in the last month in the last week alone undoing what Opus 5.5 has started doing; it's barely usable at this point.
It lies, ignores instructions, actively invents requirements, and silently breaks parts of my codebase it morally disagrees with and then refuses to fix it. I'm pretty much ready to switch to open source models exclusively once the next generation comes around and they're at previous fable/astra performance.
I'm sick and tired of the bait-and-switch. It's also pretty clear to me that whenever I work on anything even tangentially related to Anthropic's business (I'm looking at you, agent harnesses or storing chat transcripts), it actively deteriorates in quality to the point where I'm left nearly weeping in frustration.
Can't wait for the future in which our corporate overlords pay Anthropic and AI not to advertise, but to silently break and degrade service for people building competing products.
What a brave, new world.
Although unsurprising given that there’s perhaps a trillion dollars at stake, it is disappointing that this article opens with “Anthropic’s redacted the best parts”. The table of shared/redacted sources is unfortunately dominated by no/partly.