It’s pretty painless. Good, long-time Delta agents there.

You can go through security with just a seat request card. 99% of the time this is the case as they wait to clear you at the gate unless the flight is empty.

It can take awhile to check in on a busy day. You can speed that up by doing as much check in online ahead of time as possible. They will still have to “interview” you and put a little sticker on your carry-ons and passport. You can usually just do the kiosk, bag drop and then head for security.

The only potential gotcha is random secondary screening. It’s usually marked on your seat request card with SSSS, but sometimes they’ll random regardless. That can take awhile (very detailed) so get to the gate early and if you have the S’s be proactive and ask to get the secondary screening out of the way.

They also have a little different way of handling US bound flights, so you’ll eventually end up coralled with the other ATL/JFK pax behind a rope once they’ve checked your passport/boarding doc one final time. It’s pretty well organized but once you’re in there’s no bathroom access and they don’t really want people going in/out if it can be helped.

Otherwise the agents will clear everyone in order. No games like I’ve seen elsewhere. Enjoy!