Without benchmarking LLMs, you're likely overpaying 5-10x

(karllorey.com)

63 points | by lorey 3 hours ago

10 comments

  • hamiltont 55 minutes ago
    Anecdotal tip on LLM-as-judge scoring - Skip the 1-10 scale, use boolean criteria instead, then weight manually e.g.

    - Did it cite the 30-day return policy? Y/N - Tone professional and empathetic? Y/N - Offered clear next steps? Y/N

    Then: 0.5 * accuracy + 0.3 * tone + 0.2 * next_steps

    Why: Reduces volatility of responses while still maintaining creativeness (temperature) needed for good intuition

    • pocketarc 48 minutes ago
      I use this approach for a ticket based customer support agent. There are a bunch of boolean checks that the LLM must pass before its response is allowed through. Some are hard fails, others, like you brought up, are just a weighted ding to the response's final score.

      Failures are fed back to the LLM so it can regenerate taking that feedback into account. People are much happier with it than I could have imagined, though it's definitely not cheap (but the cost difference is very OK for the tradeoff).

    • Imustaskforhelp 46 minutes ago
      This actually seems really good advice. I am interested how you might tweak this to things like programming languages benchmarks?

      By having independent tests and then seeing if it passes them (yes or no) and then evaluating and having some (more complicated tasks) be valued more than not or how exactly.

      • hamiltont 33 minutes ago
        Not sure I'm fully following your question, but maybe this helps:

        IME deep thinking hgas moved from upfront architecture to post-prototype analysis.

        Pre-LLM: Think hard → design carefully → write deterministic code → minor debugging

        With LLMs: Prototype fast → evaluate failures → think hard about prompts/task decomposition → iterate

        When your system logic is probabilistic, you can't fully architect in advance—you need empirical feedback. So I spend most time analyzing failure cases: "this prompt generated X which failed because Y, how do I clarify requirements?" Often I use an LLM to help debug the LLM.

        The shift: from "design away problems" to "evaluate into solutions."

    • lorey 42 minutes ago
      Yes, absolutely. This aligns with what we found. It seems to be necessary to be very clear on scoring (at least for Opus 4.5).
    • 46493168 35 minutes ago
      Isn’t this just rubrics?
  • andy99 1 hour ago
    Depends on what you’re doing. Using the smaller / cheaper LLMs will generally make it way more fragile. The article appears to focus on creating a benchmark dataset with real examples. For lots of applications, especially if you’re worried about people messing with it, about weird behavior on edge cases, about stability, you’d have to do a bunch of robustness testing as well, and bigger models will be better.

    Another big problem is it’s hard to set objectives is many cases, and for example maybe your customer service chat still passes but comes across worse for a smaller model.

    Id be careful is all.

    • candiddevmike 1 hour ago
      One point in favor of smaller/self-hosted LLMs: more consistent performance, and you control your upgrade cadence, not the model providers.

      I'd push everyone to self-host models (even if it's on a shared compute arrangement), as no enterprise I've worked with is prepared for the churn of keeping up with the hosted model release/deprecation cadence.

      • andy99 46 minutes ago
        How much you value control is one part of the optimization problem. Obviously self hosting gives you more but it costs more, and re evals, I trust GPT, Gemini, and Claude a lot more than some smaller thing I self host, and would end up wanting to do way more evals if I self hosted a smaller model.

        (Potentially interesting aside: I’d say I trust new GLM models similarly to the big 3, but they’re too big for most people to self host)

    • jmathai 39 minutes ago
      You may also be getting a worse result for higher cost.

      For a medical use case, we tested multiple Anthropic and OpenAI models as well as MedGemma. Pleasantly surprised when the LLM as Judge scored gpt5-mini as the clear winner. I don't think I would have considered using it for the specific use cases - assuming higher reasoning was necessary.

      Still waiting on human evaluation to confirm the LLM Judge was correct.

      • andy99 17 minutes ago
        You obviously know what you’re looking for better than me, but personally I’d want to see a narrative that made sense before accepting that a smaller model somehow just performs better, even if the benchmarks say so. There may be such an explanation, it feels very dicey without one.
    • lorey 38 minutes ago
      You're right. We did a few use cases and I have to admit that while customer service is easiest to explain, its where I'd also not choose the cheapest model for said reasons.
  • epolanski 1 hour ago
    The author of this post should benchmark his own blog for accessibility metrics, text contrast is dreadful..

    On the other hand, this would be interesting for measuring agents in coding tasks, but there's quite a lot of context to provide here, both input and output would be massive.

    • lorey 7 minutes ago
      Pushed a fix. Could you check, please?

      Any resources you can recommend to properly tackle this going forward?

    • lorey 37 minutes ago
      Appreciate the feedback, will work on that.
      • faeyanpiraat 27 minutes ago
        One more vote on fixing contrast from me.
        • lorey 25 minutes ago
          Will fix, thanks :)
          • faeyanpiraat 7 minutes ago
            Tried Evalry, its a really nice concept, thanks for sharing it!
  • verdverm 1 hour ago
    I'd second this wholeheartedly

    Since building a custom agent setup to replace copilot, adopting/adjusting Claude Code prompts, and giving it basic tools, gemini-3-flash is my go-to model unless I know it's a big and involved task. The model is really good at 1/10 the cost of pro, super fast by comparison, and some basic a/b testing shows little to no difference in output on the majority of tasks I used

    Cut all my subs, spend less money, don't get rate limited

    • dpoloncsak 1 hour ago
      Yeah, one of my first projects one of my buddies asked "Why aren't you using [ChatGPT 4.0] nano? It's 99% the effectiveness with 10% the price."

      I've been using the smaller models ever since. Nano/mini, flash, etc.

      • sixtyj 56 minutes ago
        Yup.

        I have found out recently that Grok-4.1-fast has similar pricing (in cents) but 10x larger context window (2M tokens instead of ~128-200k of gpt-4-1-nano). And ~4% hallucination, lowest in blind tests in LLM arena.

        • verdverm 7 minutes ago
          You use stuff from xAi and Elmo?

          I'm unwilling to look past Musk's politics, immorality, and manipulation on a global scale

      • phainopepla2 1 hour ago
        I have been benchmarking many of my use cases, and the GPT Nano models have fallen completely flat one every single except for very short summaries. I would call them 25% effectiveness at best.
      • walthamstow 1 hour ago
        Flash Lite 2.5 is an unbelievably good model for the price
    • r_lee 1 hour ago
      Plus I've found that overall with "thinking" models, it's more like for memory, not even actual perf boost, it might even be worse because if it goes even slightly wrong on the "thinking" part, it'll then commit to that for the actual response
      • verdverm 5 minutes ago
        for sure, the difference in the most recent model generations makes them far more useful for many daily tasks. This is the first gen with thinking as a significant mid-training focus and it shows

        gemini-3-flash stands well above gemini-2.5-pro

    • dingnuts 1 hour ago
      [dead]
  • gridspy 58 minutes ago
    Wow, this was some slick long form sales work. I hope your SaaS goes well. Nice one!
  • deepsquirrelnet 51 minutes ago
    This is just evaluation, not “benchmarking”. If you haven’t setup evaluation on something you’re putting into production then what are you even doing.

    Stop prompt engineering, put down the crayons. Statistical model outputs need to be evaluated.

    • andy99 45 minutes ago
      What does that look like in your opinion, what do you use?
    • lorey 35 minutes ago
      This went straight to prod, even earlier than I'd opted for. What do you mean?
  • OutOfHere 27 minutes ago
    You don't need a fancy UI to try the mini model first.
  • petcat 1 hour ago
    > He's a non-technical founder building an AI-powered business.

    It sounds like he's building some kind of ai support chat bot.

    I despise these things.

    • montroser 1 hour ago
      The whole post is just an advert for this person's startup. Their "friend" doesn't exist...
    • njhnjh 1 hour ago
      > He's a non-technical founder building an AI-powered business.

      read: he's a professional idiot

      • sullivanmatt 1 hour ago
        It's perfectly possible it's someone with deep domain experience, or someone who has product design or management skills. Regardless, dismissing these people out of pocket is not likely the best choice.
    • lorey 33 minutes ago
      Totally agree with your point. While I can't say sadly, but it's a traditional (German) business he's doing vertically integrated with AI. Customer support is really bad in this niche and by leveraging AI on top of doing the support himself 24/7, he was able to make it his competitive edge.
    • r_lee 1 hour ago
      And the whole article is about promoting his benchmarking service, of course.
  • nickphx 41 minutes ago
    ah yes... nothing like using another nondeterministic black box of nonsense to judge / rate the output of another.. then charge others for it.. lol
    • coredog64 22 minutes ago
      Amazon Bedrock Guardrails uses a purpose-built model to look for safety issues in the model inputs/outputs. While you won't get any specific guarantees from AWS, they will point you at datasets that you can use to evaluate the product and then determine if it's fit for purpose according to your risk tolerance.