I wonder if there are is a single factor that would act to make you go faster in the winter (in the absence of the billion factors that have been mentioned that will slow you down).

Sometimes there are huge winds, I guess if it's a tailwind that'll make you go faster. I've had that happen once or twice.

And then brakes failing... That could make you go faster than you would want, until something else causes you to stop

Yeah pretty bleak on the speed front.