Lowry went from wanting to get off the course as quickly as possible in the wind-blown opening round to wishing a day like this wouldn't end as he shot an eight-under round while hitting his irons so well that only three of his nine birdies were outside 10 feet.
"Every time I kept making birdie, I just kept going, wanting to birdie the next," Lowry said on Friday.
"I felt like I was in control out there. So it was good fun. It's been a while since I've had that much fun on the golf course, so I'll take it."
The popular Irishman was on 11-under 129, three shots clear of Haotong Li (63) and the Danish duo of Jacob Skov Olesen and Niklas Norgaard, who each shot 64.
Li also enjoyed a spell of good weather on the Doonbeg course along the Atlantic coast after Thursday when the wind was so strong it took some six hours to play. The first round had to be completed on Friday.
"Today it was kind of like birdie heaven," said Li.
Not for defending champion Rory McIlroy, though. He struggled to read the greens, and the 18th summed up his round of 69 when he three-putted from four feet for bogey, missing a 20-inch par putt.
"It's hard whenever you struggle to read them," McIlroy said. "And then when you do get over the ball you're trying to trust what you're seeing, but everything else that you have seen hasn't went the way you thought."
He was nine shots out of the lead and bracing for more rough weather over the weekend, when President Donald Trump is due for a visit.
Joaquin Niemann, the 18-hole leader, had to settle for a 70 that left him six shots behind. Patrick Reed, the American who leads the Race to Dubai, had another 68 and was seven shots back. Jon Rahm had a 67 and was another shot behind at three-under.
Australia's David Micheluzzi, who shot a 69, made the cut on level par, while compatriot Jason Scrivener, four-over for the tournament after a 71, missed out on the weekend.
