Flying MIA/DFW/PHX/BOI today. Despite a thunderstorm cell on the way to the MIA airport the ground crew slow at getting bags loaded so the ramp closes before they can finish. So we leave 40 minutes late. Captain apologies profusely and gets ATC approval to shorten the flight plan to DFW by 15 minutes. We land one of the outlying runways but the Captain speeds to the gate (we all know how slow taxis tend to be). So we get to the gate at DFW 20 minutes before the revised posted arrival time. Paxs are happy now, they have a chance to make connections. Then we wait nearly 20 minutes for a GA to attach the jet bridge and so much for those tight connections (luckily I had 1.5 hours for connection to PHX).