I have to agree with Paul as far as Carnival out of New York goes. We did Carnival 2003, 2004 and just this September, same scenario 90 minute or more wait. In fact the 2004 trip was delayed by a medical emergency and they told us to be at the pier no later than 8 p.m. for boarding. We didn't board until 12:30. This last cruise was at least a 90 minute wait. We did a princess out of brooklyn last year. We arrived a little after 10 and we were on board a little after 10:30. NCL the first time was maybe a 30 minute wait. The second NCL we were put in the lattitudes waiting area and waited less than 15 minutes to board. All these cruises have been out of New York. This trip with Carnival they were still disembarking passengers at 1 p.m.
Don't forget too that you are at the mercy of US customs. If they delay people disembarking, embarking passengers are going to be delayed.