GPT-5.5 Codex Performance Issues
Executive Summary:
- GPT-5.5 Codex users are experiencing degraded performance and token issues.
- Some users have reported a significant decrease in code quality and token usage.
- OpenAI has not yet addressed the issue, leading some users to switch to alternative services.
The Internet’s Verdict: 70% Hyped, 30% Skeptical
Introduction to GPT-5.5 Codex Issues
Recently, several GPT-5.5 Codex users have come forward to report issues with the service’s performance.
Token Usage and Code Quality
Users have noticed a significant decrease in code quality and token usage, with some reporting that the service is producing
I’ve definitely experienced step jumps down in quality on an almost daily basis. I usually used xhigh. The experience of relying on codex’s outstandingly thorough coding earlier in the year has evaporated for me.
Another user stated that
Maybe its just bad memory but I feel like 5.3 was the best version in terms of token usage and code quality. 5.5 works better but it just eviscerates tokens.
Adaptive Thinking and Token Limits
Some users have also reported issues with adaptive thinking and token limits, with one user noting that
Oh this seems bad, and is fairly easy to reproduce using codex cli. You give it a puzzle prompt that it has to reason about and solve, occasionally it will seemingly short circuit and think for exactly 516 tokens, and return the wrong result.
Another user suggested that
Clearly they are batching reasoning inference in a few multiples of 512 tokens as a throughput optimization
, which may be contributing to the issue.
Focus Keyword: GPT-5.5 Codex
