GPT-5.5 Codex Performance Potentially Degraded by Reasoning-Token Clustering

Core summary

One sentence to understand this update

Reports and discussions suggest that reasoning-token clustering in GPT-5.5 Codex might be contributing to a degradation in its overall performance.

Impact & opportunity

What this could mean

Developers relying on GPT-5.5 Codex for critical development should closely monitor model performance and consider evaluating alternative models or optimization strategies if degradation is observed.