I'm assuming you live in San Francisco? As a visitor, it seemed to me that this was more due to the insane car-bus road-sharing conflicts, the inability of Muni buses to accelerate up a hill, and the deluge of 4-way stops.

Nope. Chicago suburbs, actually. But that's how long the buses take out here in the suburbs, and how long it's taken me in downtown Chicago before. I don't go on the buses that often, and this is one reason why.

The buses can have 20-40 stops in those 4 miles, mind you. I don't mean it's all due to traffic.