My commute is about 25 km each direction, from suburbs into/through the center of a major city. Takes about 1.0 - 1.05 under summer conditions. Depending on attitude and company.
Winters, and firm, smooth roads, 1.05 - 1.10.
The cost of the studded tires.
Add snow and all bets are off. 2-3" of snow to plow through can easily push the time into 1.30 and beyond, at which point I switch to public transport instead.
With public transportation, it's abt 50 minutes door-to-door. So even at the best of time, cycling does add some time. Particularly when you add shower and change time.