I have access to codex with gpt 5.4 and Claude code cli with opus 4.6 I gave them both the same problem, starting files and prompt. The task was pretty simple - write a basic parser for an EDA tool file format to make some specific mods to the file and write it out. I expected to be impressed by gpt5.4, but it ended up creating a complex parser that took over 10 mins to parse a 200MB file, before I killed it. Opus 4.6 wrote a basic parser that did the job in a kit 4 seconds. Even after pointing it out to gpt5.4 that the task didn’t need a complex solution, and it doing a full rewrite, it failed to run in under 5 mins so I killed it again, and didn’t bother trying to get it over the line. Is this common that there can be such a wide disparity? submitted by /u/mother_a_god
Originally posted by u/mother_a_god on r/ClaudeCode