There are two conclusions one can draw from this: either the idle power consumption of laptops is so low that something as trivial as updating the clock display

There are two conclusions one can draw from this: either the idle power consumption of laptops is so low that something as trivial as updating the clock display on an otherwise idle system[1] is a significant amount, or their code is so shitty that it's taking an order of magnitude or more power than it should. Given this is Microsoft, I'm inclined to believe the latter, or that it was "deliberately" implemented in an inefficient way to "prove" their argument. It'd be trivial to write a tiny Win32 app that just has an incrementing seconds counter and use that to distinguish the latter two cases. [1] The caveat is that the majority of the time the system will not be idle but doing something else possibly even more energy-intensive.