AI Slows Down Senior Devs by 19%? A Rigorous Post-Mortem of METR's Randomized Controlled Trial

TL;DRMETR conducted a Randomized Controlled Trial (RCT) involving 16 experienced open-source maintainers (each with 1M+ lines of code under their belt), putting them through 246 real-world tasks in an A/B test. The group allowed to use AI (Cursor Pro...