Since there's no such thing as a free lunch, more engine power requires more air and fuel, which you are observing as more throttle required. (mechanics.stackexchange.com)
Driving through snow of any thickness is increasing the rolling resistance of the vehicle, meaning you will need to use more engine power just to maintain your speed. (mechanics.stackexchange.com)
Conversely, when more engine power is required, the intake valve lift is increased. (autospeed.com)