Anthropic dropped Opus 5.5 a few days ago ( https://www.anthropic.com/claude-opus-5-5 ) and the numbers are kind of wild if you take them at face value. 40% cheaper to run than Opus 5, output generation 30%+ faster, and it’s landing around Fable 5.1’s level on most benchmarks while beating GPT-6 Astra on a lot of them too (not all, Astra still wins a couple). I don’t fully trust benchmarks on their own, but what’s actually got me curious is that a bunch of people using these models for real work, not hype accounts, actual devs and companies, are independently saying the same thing: cheaper, faster, and just as good or better. Normally you get to pick two out of three, not all three at once. So genuinely, how do you even pull that off? A few things I’m wondering about: Is this just a fresh pretraining run on a bigger or cleaner dataset, and the efficiency gains are more of a side effect of that rather than the actual goal? Is it mostly a post training / RL thing, where the model didn’t get “smarter” from scratch but just got way better at using the compute it has? Is some form of distillation happening, where they’re compressing a larger internal model’s capability into something cheaper to serve? Is it inference side stuff, better caching, speculative decoding, smarter routing, that kind of thing, separate from anything about the model itself? Or is there something more fundamental going on with how the model processes stuff, like some form of looped or recurrent depth transformer where it reuses layers/weights instead of just stacking more of them? I know that’s a real research direction some labs have poked at, not saying it’s confirmed for Opus 5.5, just wondering if people think it’s plausible here or if it’s more likely a mix of the boring stuff above. Anthropic doesn’t publish architecture details so I’m not expecting anyone to leak anything, just want to hear from people who actually know this stuff. If any ML folks or people who’ve worked on model efficiency want to break down what’s realistic here versus what’s just marketing, I’d genuinely love to read it. submitted by /u/Witty_County5128
Originally posted by u/Witty_County5128 on r/ArtificialInteligence