I'm planning a trip from Prague to NYC this summer. There is a direct flight to JFK and numerous transfer options. I've heard that JFK's customs can be a nightmare for non-US citizens and therefore considering routing my flight through Dublin where you can go through the TSA preclearance facility.
Will I save much time by doing so?
Being a frequent transatlantic passenger to New York from UK I have many experiences of customs and immigration in USA. I have done both scenarios several times. Because of my origin location, flight time is roughly the same:
What I find quicker by an average of an hour is the lack of queue at Dublin for pre clearance checks. Time I would be using in Amsterdam or Heathrow to browse the selection of shops and restaurants before my connection is now spent pre clearing immigration in Dublin.
I haven't done pre-clearance in Dublin -- but I have done it in Toronto. It seemed to go faster than immigration in New York or Atlanta, based on my (limited) experience.
But I'd still caution against it: If you hit a delay at a transfer point, causing you to miss a flight, it can be frustrating and/or expensive. And adding an unknown such as 2 immigration checks (Ireland from the Czech Republic, and then USA from Ireland) will have the potential to mess up your trip -- unless you budget so much time for it that you really won't save any time at all: You'll just end up spending that time for certain in the Dublin Airport, rather than potentially in line at JFK.
