I live in a Rust Belt city and bike everywhere. One of my common rides is five miles one way.
It's very common for me to be riding along the same cars from my house to destination, with a little back and forth leapfrogging. Turns out their average speed is similar to cycling.
With traffic lights, jams, bus stops, etc.. it does slow them down tremendously. Of course bikes can go through jams and lights willy nilly.
My job was 6 miles from home by car and 45min (some quite stressful), I actually took a longer path (7miles) by bike to enjoy a river path, took me 40min to arrive.
Initially, perhaps, but riding such hills regularly is a pretty good way to build up leg strength (and confidence descending) to the point small hills aren't really going to slow you down much. Traffic (+ stop lights) is far and away the biggest thing that slows me down on a bike - I can average 5 k/h faster once away from heavily congested areas with frequent stops required. In my city at least those less congested areas are the hillier ones!
I used to dread hills even as an avid bicyclist, but as soon as I had three big ones on my daily route my body just adapted. So yes topography does affect your choices less people will cycle there, but it does not affect time that much.
