Unverified50% confidenceFactExact time
In a rigorous trial, experienced developers using AI tools on their own mature codebase were 19% slower, yet they themselves believed they were 20% faster.
1
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50%
Confidence
Long-term
Relevance
10/19/2026
First Seen
Sources
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Related Claims
UnverifiedOn July 10, 2025, METR published a randomized controlled trial: 16 senior open-source developers handled 246 tasks on real repositories, and after using AI tools they were actually 19% slower, despite prior expectations of a 24% speedup and post-hoc self-reported estimates of a 20% speedup.80% similarUnverifiedA study by METR found that senior engineers using AI for certain tasks were actually 19% slower, because time was spent on validation and correction.79% similarUnverifiedIn METR's early 2025 trial, when AI use was allowed, task time actually increased by 19%, while developers had predicted beforehand that AI would speed them up by 24% and afterward still believed they had been sped up by 20%.77% similarUnverifiedIn a controlled writing experiment, professionals using AI completed tasks 40% faster and improved quality by 18%.76% similarUnverifiedIncorporating an encoder into the architecture yields a rough estimated inference speed improvement of approximately 25%, as the amount of computation is reduced by roughly one quarter.76% similar
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