Inception just dropped Mercury 3, a model 4-8x faster than Luna / Haiku for the same price and benchmark performance.

In real world use, OpenRouter shows that it’s effectively 2-4x faster and 2-4x cheaper effective price.

The time for diffusion language models is finally here!

Oct 20, 2026 · 7:33 AM UTC

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Replying to @deedydas
Source:
Mercury 3 is live: the most capable diffusion LLM released to date.

It outperforms GPT-6 Luna and Claude Haiku 5.5 across a range of benchmarks while running at over 1,000 tokens per second.

More than 40x the size of Mercury 1, 3x more intelligent across standard benchmarks, a 1M-token context window.

Available today on the Inception API, @baseten, and @OpenRouter .
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Replying to @deedydas
@deedydas will swap it into my agent loop tonight
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Replying to @deedydas
@deedydas we just need fable 5.5 diffusion model from claude at 2k tps and then everyone wins
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Replying to @deedydas
@deedydas Still not fast enough for the performance compromise!
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Replying to @deedydas
@deedydas Diffusion LMs having a real moment is the actual story here, benchmarks aside. If parallel decoding holds quality at 4x the speed, autoregressive's monopoly on "good enough" might finally be over.
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Replying to @deedydas
@deedydas this is the subagent model. file search and test loops don't need opus.

anyone running mercury 3 as the cheap worker inside codex or claude code yet?
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Replying to @deedydas
@deedydas Diffusion is coming!
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Replying to @deedydas
@deedydas mercury 2 and 2.5 are already closed to new users, and existing api customers lose access nov 15
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Replying to @deedydas
@deedydas The part that makes this more than a speed demo: Mercury 3 is 40x the size of Mercury 1 and just as fast. If that holds, diffusion LLMs get smarter without paying for it in latency.
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Replying to @deedydas
@deedydas Sub-$0.40 output at 300+ tok/s while matching Haiku/Luna benchmarks... the inference speed war is getting crazy.
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Replying to @deedydas
@deedydas Mercury 3 is cheaper and faster. Other AI companies must be furious someone tried both.
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Replying to @deedydas
@deedydas diffusion models being 4x faster means the loading spinner finally gets to retire
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Replying to @deedydas
@deedydas 4-8x faster and my agent will still spend it rereading the same file
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Replying to @deedydas
@deedydas A split that works well: the fast model as the worker for search, small edits and test-fix loops, the big model only to plan and to review the final diff. Speed where you wait, smarts where you decide.
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Replying to @deedydas
@deedydas 2-4x cheaper at the same quality is the part that actually changes buying decisions.
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Replying to @deedydas
@deedydas Mercury 3 sounds like it skipped the line at the token counter.
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Replying to @deedydas
@deedydas Most of the 2-4x is input: $0.022 vs $0.043 for Luna and $0.086 for Haiku in your OpenRouter chart. Output is $0.36 vs $0.45 and $0.57, only 1.3-1.6x. Output-heavy agent runs get the smaller number.
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Replying to @deedydas
@deedydas Agent loops chaining dozens of tool calls will notice this speedup way more than anyone just chatting with it.
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Replying to @deedydas
@deedydas 2-4x cheaper in real traffic is what'll get people switching.
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Replying to @deedydas
@deedydas Man I wish it was actually good... Idk if it's just launch issues or what but my benchmarks of it are extremely swingy on latency. Taking as much as 5x longer for the same prompt within seconds randomly and regularly
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Runway is now in GPT-6 Astra. Ask for a video in ChatGPT and Runway makes it. Multi-shot, same cast, in the thread.
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Replying to @deedydas
@deedydas 2-4x faster in real use at Haiku level is already huge. Speed irons out so many of the small issues, can't wait to see diffusion models go further
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Replying to @deedydas
@deedydas Great breakdown. Mercury 3 sounds like a real step change for diffusion LMs. @88krxxs will want to see this.
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Replying to @deedydas
@deedydas Diffusion LMs write the whole answer at once, like a polaroid developing. Token streaming suddenly looks like a typewriter 🙂
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Replying to @deedydas
@deedydas 2-4x faster and cheaper on OpenRouter is actually the part that matters most for real work right now. Performance benchmarks are nice but speed/cost wins in deployment.
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Replying to @deedydas
@deedydas in my agent loops one extra wrong turn would eat that whole speedup pretty fast
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Replying to @deedydas
@deedydas the whole answer just appearing at once is gonna feel so weird in a chat ui ngl
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Replying to @deedydas
@deedydas the benchmark charts dont have a speed axis
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Replying to @deedydas
@deedydas 2-4x on openrouter next to 4-8x on the lab chart, i'll take the openrouter one
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Replying to @deedydas
@deedydas The OpenRouter numbers matter more than the benchmark. 2-4x cheaper in real use can actually change model routing.
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Replying to @deedydas
@deedydas same price at 4x the speed makes it a scout model candidate
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Replying to @deedydas
@deedydas speed only matters to me if it returns the same structure every time, a fast model I have to retry twice isnt actually faster
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Replying to @deedydas
@deedydas 4 to 8x faster at the same price. Would you switch your default model for speed alone?
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Replying to @deedydas
@deedydas 拡散LLMが速いのは分かるけど、私は節約でモデルを安く替えたのに、検証し直す手間で結局コストが増えて転んだから、本番投入前の品質確認が一番怖い。
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Replying to @deedydas
@deedydas It kinda does not work at all.
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