I would agree that Delta is probably the longest line at the port. And it did take us somewhere in that same neighborhood to go through it.
But, I spoke with a couple of people at the airport who were flying Delta and checked in at the airport. It took them an hour and a half! Which doesn't surprise me for MCO. Remember that first you have to stand in line to check in at the desk and get your boarding pass. Then you have to stand in another line with all your bags to have them screened. By checking in at the port you bypass that second line.
The porters that collect your bags will take them right up to an area next to the check in podium while you get in line. Then when you are up to the podium the airline representative gives you your borading passes and puts the check baggage strips on the luggage. Because it theoretically hasn't been in your control - or at least not in a situation where you could really do anything with it of a negative nature from the time it came off the ship and has already been screened by customs they simply take it to the airport.
We did find that TSA opened and checked one of our bags - upon review I realized that packing most of the shoes, along with books, a metal makeup case, batteries, the extension cord, hairdryer, curling iron, etc - you get the idea in the same bag probably looked pretty weird on X-ray!
Deb