GPT-5.5 Codex Performance May Degrade Due to Reasoning-Token Clustering

Core summary

One sentence to understand this update

Discussions suggest that reasoning-token clustering in GPT-5.5 Codex models might be causing degraded performance, drawing attention from the technical community.

Impact & opportunity

What this could mean

Builders relying on GPT-5.5 Codex for code generation or complex reasoning tasks should be aware of potential performance issues and consider adjusting prompting strategies or exploring alternatives.