Measuring the Impact of Early-2025 AI on Experienced Open-Source Developer Productivity

"When developers are allowed to use AI tools, they take 19% longer to complete issues—a significant slowdown that goes against developer beliefs and expert forecasts. This gap between perception and reality is striking: developers expected AI to speed them up by 24%, and even after experiencing the slowdown, they still believed AI had sped them up by 20%."

Like so many papers on AI, this ignores the ethical aspects and any power analysis -- which would be just as problematic if AI tools actually made experienced developers faster. So it's the gap between perception and reality that I find most interesting. Keep that in mind when you see developers -- or anybody else -- talking about how amazingly more productive they are thanks to AI!