One of the greatest threats to performance is a simple element of human nature most often referred to Parkinsons Law. “Work expands so as to fill the time available for its completion” there is much more to this law, in order for the work to expand other things must expand also, for the work to expand other elements relating to the work must expand also, complexity expands, capabilities expend.
So here we hit the joys of Agile, Agile uses short focused time boxes in terms of the daily cycle or the longer iteration or sprint cycle. That short cycle, those tight time boxes mean that you only have time to focus on what’s needed, what must happen. you can only focus on the musts (MSCW), so forcing the delivery to be quick, to be focused, elegant and , ensuring absence of waste(no time for extras) and absence of complexity.
Thus one of the great advantages of Agile is that is specifically addresses Parkinsons Law, Agile and specifically time boxes better focus the team. Its better to under deliver (just enough but not to much) than over deliver.