
VulcanBench
458 posts

VulcanBench
@VulcanBench
Open Source LLM benchmarking tool, focused on real world tests, large codebases, full transparency. An Open Source project by @morganlinton.





Just finished my first set of benchmarks comparing Sonnet 5 and Opus 4.8 on @VulcanBench across effort levels. This is the first of a number of benchmarks I plan on doing with Sonnet 5, but I wanted to get something kinda unique and different out there. And yes, don't worry, I'll do a GLM 5.2 comparison. I don't think many benchmarks are looking at how changing effort levels impacts accuracy, so I thought this could be an interesting angle to start with. In total I ran 936 test runs across both models, and three different effort levels. Here's the high-level results, will be sharing a more detailed overview in a full report tomorrow: 💸 Sonnet 5 matches Opus 4.8's accuracy at roughly HALF the cost per run. 🎯 Sonnet 5 at high effort is the only config to solve all 52 tasks (100%), and it still costs less than Opus at high effort. 📈 Reasoning effort scales Sonnet 5 (97 to 100%) but does nothing for Opus 4.8 (flat 97 to 98%). Extra thinking is wasted on Opus here. 🧮 Every single Opus cell is Pareto-dominated on cost vs quality. ⚡ Opus's one edge: fewer tokens, faster runs. Sonnet "thinks" ~2x harder at high effort but wins on price anyway (its tokens are 3/5 the cost). ⚠️ Honesty check: this suite saturates the frontier, so the accuracy gaps are tiny (1 to 3 tasks). The real signal is cost and how each model responds to effort, not raw capability. And please remember, I'm not some kind of benchmarking expert, this is new territory for me so I'm testing and learning as I go. Still working on updated evals that will be harder for these models so I can start to get scores in the 80% - 90% range. That being said, some interesting insights from this benchmark run, and gives me a lot more ideas for the next run!

Sonnet 5 medium is better than GLM 5.2 high and roughly the same price hilarious tbh



Running a number of benchmarks on Sonnet 5, the first one, is something unique I don't think anyone else is benchmarking right now. Evals looking at Opus 4.8 vs. Sonnet 5, across reasoning levels. My theory is that you can use Sonnet 5 in cases where you used to use Opus 4.8, but I'm curious what level of reasoning you can get away with. Most people never even try Low or Medium, I want to see if it might be time to dip back into the lower effort bucket with this model. Here's a rundown of what I'm going to test:

Claude Sonnet 5 is here. Top-tier performance on coding and tool use at Sonnet pricing, with a 1M context window. It's the new default in Claude Code for Pro users, and available everywhere on the Claude Platform, including the API and Managed Agents.











Introducing a limited preview of GPT-5.6 Sol, our next generation frontier model, as well as GPT-5.6 Terra, a balanced model for efficient, everyday work, and GPT-5.6 Luna, a fast and affordable model for high-volume work. openai.com/index/previewi…









