What does GRUB2 do when there's nothing to do?

[Philip Rowlands]

When testing with many different kernels installed, I often interrupt the menu 
timeout then make a cup of tea, or become otherwise distracted.

When this happens, GRUB2 is waiting for keyboard input but also appears to be 
consuming power, judging by the way the fans speed up. (Optiplex 7090, if it 
makes a difference.)

Is there any config around polling / power saving, or any interactive commands 
which would show relevant settings? In Linux I'd be looking at P-states and 
C-states, but options are limited from the bootloader.

Cheers,
Phil