GPT-5.5 Codex performance degradation linked to reasoning-token clustering
July 4, 2026
Metadata analysis of GPT-5.5 Codex shows reasoning_output_tokens disproportionately clustering at fixed intervals of 516, 1034, and 1552. This pattern correlates with lower reasoning intensity and potential performance drops on complex reasoning tasks.
HOW THIS AFFECTS YOU
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builderYou should monitor reasoning token counts for unexpected patterns that may signal degraded model output.
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researcherThis provides evidence of potential architectural bottlenecks in how reasoning tokens are sampled or structured.