You can make that hike from the base of the chair in only five minutes longer than it takes to ride the lift? That's impressive. It's almost a mile in length. 15 minutes is a brisk paced mile while walking on pavement in street shoes. Average person does that in about 20 minutes.
Up a steep snowy hill, in ski boots with skis on my back, I would figure closer to 30 minutes
What do you mean from the base of the chair? You take the Heaven's Gate triple to the top of Lincoln Peak, then start down Paradise and cut off onto the Long Trail and basically hike alone the ridge over to CR. Sure the Long Trail has both some downhill and uphill sections and isn't flat...but you're not really hiking up a steep snowy hill.