So, we passed through JFK Airport last month on our return from Europe and it took two hours from the time the plane landed to get through passport control. The wait in the cramped tunnel was awful as it was packed with hundreds of passengers, limited garbled instructions from staff and virtually no ventilation. We have avoided this airport in the past, is there hope JFK Airport will improve?
In one word....no...
JFK is a massive airport, with eight separate terminals, a lot of those terminals have their own immigration/customs halls. Thus, each terminal is like an airport within an airport. Since it's so massive each time you pass through and use a different terminal your experience could be radically different.
Personally I avoid large airports like JFK, Heathrow, and LAX like the plague. If given a choice I use smaller airports like Newark, Gatwick, or John Wayne, they're smaller and easier to navigate.
Next time you have to pass through NYC try Newark instead. I think you'll be pleasantly surprised.