Ask HN: Is Opus 5.5 another step change?

This feels like another moment, like earlier this year, and the year prior. I am thrilled for my use cases in the applications that I build with CC, and for the LLM API usage that I sell. However, it honestly scares the crap out out of me.

Is "the exponential" an actual thing?

Comments

A_D_E_P_TSep 25, 2026, 10:50 PM
Yes, Opus 5.5 and Astra-6 are big improvements over Opus 5 and Sol-5.6. I'm at a point where I can automate much of my workflow, even for complicated tasks, which I could never do before.

Also the new Xiaomi model, Mimo v2.6, is outstanding as a light and cheap model. For coding, the new meta is using Astra-6-Max for orchestration and architecture, and Mimo for grunt work.

nr378Sep 26, 2026, 12:22 AM
Yep, I'm personally finding Opus 5.5 to be the first real leap I've felt since Opus 4.5. The time-to-first-token seems dramatically better in Claude Code compared to Fable 5.1/Opus 5 as well, which really helps both interactivity and also overall time-to-completion.

It also burns Claude subscription quota much more slowly than Fable, which is nice.

iliedanilaSep 27, 2026, 7:47 PM
I find that Opus 5.5 compared to previous versions (after 4.6) is the first update in the right direction.
jryan49Sep 26, 2026, 12:28 PM
I have Opus 5.5 running subagents for the last 20h without any input from me after developing a plan and it seems to be going well somehow... but I will find out soon...
MoneyLovesSpeedSep 26, 2026, 2:28 PM
20h with no input is insane

at that point the hard part is just trusting it didnt quietly go off track somewhere imo

jryan49Sep 26, 2026, 5:29 PM
I've been checking it and it's doing great I'm sure there are some bugs but it's doing a huge bulk of tedious simulation logic for my game. I was previous in the loop quite a bit but I found myself never having to redirect it so I tried the here a giant plan /loop until its done
tkgallySep 26, 2026, 1:23 AM
I’m also finding Opus 5.5 to be a significant advance. In the past few days, I’ve given it several complex tasks related to two long-term dictionary-building projects [1, 2], and it handled them impressively—similar to Fable but with much lower token consumption. It also communicates better than Opus 5.1; I don’t think I’ve seen any obvious Claudisms yet.

[1] https://www.tkgje.jp/

[2] https://tkgally.github.io/eex-dict/index.html

fullstackwifeSep 27, 2026, 2:07 PM
I stopped thinking that much about quota usage, there is less of accidental +10% weekly quota in 5 minutes.
KellyCriterionSep 26, 2026, 1:13 PM
First of all, I consider it very expensive, somehow in the range of Fable:

I activated Opus 5.5 when the invitation popup showed up, and Im already paying as a pro-user - nontheless the usage of Opus 5.5 charged massivly additional on the last few days, around 12-13 USD per day.

Im still fine with Opus 4.6 or 4.8 for daily development.

JojoFatsaniSep 26, 2026, 3:09 AM
I just love that it knows how to form its thoughts into meaningful statements without rambling again.
sznioSep 26, 2026, 6:16 AM
It's the first model that I feel I can just use freely without crashing into the 5 hour limits. I just manage to get my work done and still have tokens left over
brianwawokSep 26, 2026, 1:05 AM
Feels like a faster and cheaper fable, which yes is a big jump.
Ebrahim6677Sep 27, 2026, 3:24 PM
well, not really , it is not that much of big step.
smnplkSep 26, 2026, 12:12 AM
yea, apparently you dont need to know Rust
grim_ioSep 25, 2026, 11:47 PM
It's less shit, so that's good I think.
m4rtinkSep 25, 2026, 11:41 PM
No. Next question ?
moomoo11Sep 26, 2026, 2:13 PM
astra on ultra still blows it out of the water
amina124Sep 27, 2026, 6:31 PM
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sur_lalSep 26, 2026, 12:32 PM
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aniu005Sep 27, 2026, 6:34 AM
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kylehotchkissSep 26, 2026, 3:17 AM
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