Codex gpt-5.5-xhigh Performance Tracker

Last updated: Apr 30, 2026

The goal of this tracker is to detect statistically significant degradations in Codex with gpt-5.5-xhigh performance on SWE tasks.

• Updated daily: Daily benchmarks on a curated subset of SWE-Bench-Pro
• Detect degradation: Statistical testing for degradation detection
• What you see is what you get: We benchmark in Codex CLI with gpt-5.5-xhigh directly, no custom harnesses.

New model — collecting baseline data. Degradation detection paused. View historical performance.

Collecting...

new baseline

55 %

50 eval test cases ran

54 %

300 eval test cases ran

55 %

1,300 eval test cases ran

Pass rate over time

Toggle 95% CI to view uncertainty around each point.

Pass Rate

Daily benchmark pass rate showing the percentage of tasks solved each day.

95% CI

95% confidence interval for each data point. Toggle checkbox to show/hide. Wider intervals indicate more uncertainty (fewer samples).

Enable 95% CI checkbox to show confidence intervals

Aggregated 7-day pass rate

The same uncertainty toggle applies here for 7-day windows.

Pass Rate

7-day rolling pass rate aggregating daily results for a smoother trend view.

95% CI

95% confidence interval for each data point. Toggle checkbox to show/hide. Wider intervals indicate more uncertainty (fewer samples).

Enable 95% CI checkbox to show confidence intervals

We'll email you when we detect a statistically significant performance drop.

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