There were reports of people missing their flights as a result of delays.
The Dubin Airport Authority has apologised for the long wait times at security on Sunday.
They said the delays were caused by a 'log jam' in getting new staff in.
The airport management company says over 100 new staff have been added since the New Year.
But there's been trouble getting them started due to regulations.
The delays at Dublin Airport were compounded by a drone flying over the airfield on Sunday.
It grounded several flights for about 20 minutes yesterday.
— Ertan Sahin (@sahiner1) March 27, 2022
An airport spokesperson said the safety and security of all airport users was their primary concern.
Amateur Golfer Hugh Foley missed a flight on Sunday because of the delays.
"Around terminal one it's crazy. I fly a lot and honestly, I've never seen it like it," he said.
"In terminal one, the queue is zig-zagging through every checking desk all the way back to Ryanair."
"I actually saw Gardaí walking around here because I imagine the patience of thousands of people was being tested."