Never ever take the Dublin to Chicago Airlingus Flight 92.
This Christmas I and the wife decided to save some time, I’ve been working in Dublin this fall, and the idea of driving to Cork to pickup the wife and drive to Shannon to catch flight 92 seemed too much work. So the wife took the train to Dublin, and we would catch the flight at Dublin after a short taxi ride. Knowing that we needed to get to the checkin early, I got us to the airport with three hours till the flight. Waiting in the nearly empty queue, watching a thousand others in their queues, I thought I was smart. We checked in with ease, and then spent the next two and half hours waiting on a plane arriving thirty minutes late. No bother we got on the plane for a thirty minute flight to Shannon, where we were instructed to deplane for an hour trip through customs.
We could have slept in and driven to Shannon and had a good lunch in less time then we wasted in Dublin. Take a bus, drive yourself, if you have to go through Shannon customs just to get to the U.S. save yourself the pain, don’t fly out of Dublin.
You need to check in advance what the routing is on your flight since I have been on flights to the US from Shannon which went to bloody Dublin on the way (and we had to disembark in Dublin to do Immigration).