Scheffler, world number one and 2022 Masters champion, completed a bogey-free round of 16.
“Scottie does a really good job,” McIlroy said. “It doesn’t seem like it’s six under par, and then at the end of the day, it’s six under par. He’s so efficient at everything.
“If you look at Scottie compared to the rest of the field, the number of bogey-free rounds he shoots is phenomenal.
“That’s the secret to winning major championships and important golf tournaments: it’s more about limiting mistakes than making a ton of birdies.
“I made three bogeys today, which is good in these conditions, but I just need to put some order in to try and keep up with it.”
Play will resume at 12:50 BST on Friday as some players complete their first round.
McIlroy is scheduled to begin his second round at 18:48.