Updated
Which AI model writes the most performance bugs?
As of Nov 14, 2026, GPT-6 Astra had the highest rate of performance bugs (1.26, 26% above the all-model rate), statistically tied with GPT-6.1 Sol, Claude Sonnet 5.5, and Claude Opus 5.5. Claude Fable 5.1 had the lowest (0.72, 28% below average), statistically tied with GPT-6.1 Sol and Claude Sonnet 5.5.
| Rank | Model | Rate |
|---|---|---|
| 1= (statistically tied) | Claude Fable 5.1 | 0.72 |
| 2= (statistically tied) | GPT-6.1 Sol | 0.98 |
| 3= (statistically tied) | Claude Sonnet 5.5 | 1.05 |
| 4= (statistically tied) | Claude Opus 5.5 | 1.19 |
| 5= (statistically tied) | GPT-6 Astra | 1.26 |
1.00 = all-model rate · lower is better · = statistically tied