One test found a 4.3x speed gap between coding agent setups

Someone ran the same coding task through ten different model and harness pairings and posted the timing data. The task: build something in Three.js. The pairings spanned Codex, OpenCode, OMP, and DSH/PTC, running models including GLM 5.3 Flash Max, Luna 5.6 Max, SOL 5.6 Max, Astra 6.0 Max, and Qwen 3.8 27B, per the independent test.

Qwen 3.8 27B on OpenCode finished in 8 minutes 48 seconds. Astra 6.0 Max on Codex, a larger model on a different harness, took 37 minutes 30 seconds for the same prompt. That's a 4.3x spread on identical work.

Token efficiency told a similar story. Luna 5.6 Max on Codex used the fewest tokens of the ten runs, 1,172,267. GLM 5.3 Flash Max on OpenCode hit 96.89% cached input, meaning almost none of its context had to be reprocessed from scratch.

None of this tracked model size or reputation. The harness, meaning which tool is managing the agent's file edits, context, and tool calls around the model, moved the numbers more than which model sat inside it did.

That's a problem for how most people evaluate these tools. Benchmarks and vendor pages compare models. Nobody's comparing harnesses, because harnesses don't have leaderboards. If you're choosing between Codex, OpenCode, OMP, or something like DSH/PTC for actual coding work, the model you plug in might matter less than which of those four you picked. One test on one task isn't a verdict on any of them, but it's a variable worth checking before you assume the model name on the box is what you're paying for.