I find that this one may make the biggest difference of all. My commute has a lot of lights and stop signs (and I actually stop). I can clear about the same distance in 1/2 to 2/3 the time on a MUP where I don't have to stop constantly (I don't particularly mind the stopping--gives me a chance to catch my breath and then practice sprinting). Even with all the stops, my hilly 5.6 miles takes just over 30 min, so the time frame you're shooting for should be very do-able, even in city conditions.