“When AI is allowed, developers spend less time actively coding and searching for/reading information, and instead spend time prompting AI, waiting on and reviewing AI outputs, and idle.”
A randomized controlled study of 16 experienced developers across 246 real issues found AI coding tools made them 19% slower. The best part is the developers predicted a 24% speedup and believed AI was helping even as it dragged them down. They rejected 56% of suggestions outright. The study specifically tested experienced devs on large codebases they already knew well, which is exactly the scenario where AI hype promised the biggest gains.