how efficient are controllers (brushless, at reduced throttle?)

[kraeuterbutter]

how efficienct are they ?

for example:
going with 15km/h does need less energy for same distance than going with 25km/h because of the airdrag..

so: let say at 25km/h controller runs "full throttle"

at 15km/h is has to reduce throttle (and for that you hear it "iiiiiiihhhhh")

will the profit of less air-drag compensate the lesser efficience of the controller?

i think so, because my controller on steep hills (were it has to reduce throttle very much to stay under his amp-limit)
gets ~60°C warm...

250g controller (= controller + aluminium case for cooling effect)
brought to 60°C
that can not be that much energy, that is wasted...
or am i mistaken ?

--------------------------------------------
other situation:
going up a hill:
would it be better to go up there with let say 12km/h and a comfortable gearing for me
so the controller has to throttle down very much
(to stay under - let say - 14A)

or would it be better to do more effort, so the controller can run faster (let say 16km/h), but still reducing to stay under - let say also - 14A
i think, even when iam pedaling harder the motor will need more electricity in this situation..
will the "going faster up and for that shorter runtime" compensate the higher energy-consumption ?