Gusts of up to 35 miles per hour saw balls oscillating on greens, with Frenchman Frederic Lacroix seeing his blown off the putting surface at the 13th, but he had fortunately already marked so was able to replace it.
All of which made for slow going at the DP World Tour event at Trump International Golf Links and Hotel in Doonbeg during Thursday's first round.
As the day wore on, a course-record 65 from Chilean Joaquin Niemann looked increasingly good.
Having reached the turn at two under, the LIV Golf star had four successive birdies from the 14th to put him in contention for a $30,000 ($A42 million) bonus for the lowest round of the week.
Poland's Adrian Meronk, who has played 15 holes, Austrian Maximilian Steinlechner (through 13) and Renato Paratore (through 12) all later made a challenge for the top of the leaderboard at three under before play was suspended just ahead of 8pm.
"There were a couple of things that were tough today. Obviously the wind and the strength of the wind was one thing and then the pace of play," McIlroy said.
"This course isn't conducive to sort of letting you get in a flow. Especially the first two days with so many people in the field, there is a lot of stopping and starting.
"I hung in there, shot under par, and at least don't feel like I am out of the tournament. A good day tomorrow gets me right back in it."Â
The Australian challenge was led by Daniel Hillier, whose one-under 69 left him four behind Niemann.
David Micheluzzi (71) is the next best Australian.
