Shot placement. If you are hitting where you want, most combo's these days produce plenty oomph for bowhunting. If you play with the KE calculators, you'll see speed and weight is relevant. A deer can jump string of the fastest bows produced.
I'm sure you know how to dress to keep warm. But you need to practice shooting with your hunting clothes on. You don't want your clothes slapping the string. Find the food sources in your area at the respective time of year. Cold weather means food sources. Find them and wait for a shot.