> To compute the actual speedup – or, rather, slowdown! – provided by AI tools, the researchers compared the developers’ predictions of how long each task would take to the measured completion time.
I'm sorry, but it feels to me like this research has only proven that developers tend to underestimate how long a task is supposed to take, with or without AI.
In no way did they actually measure how much faster a specific task was when performed with and without AI?