The former Auckland Blue bagged himself 20 points in the process including a try, three conversions and three penalties.
"Isa orchestrated things from the back. I thought he did okay. He's not bad," joked Schmidt.
"You've got to temper any excitement with the opposition. They were very short on personnel and training time and it is very cold where they are."
An inexperienced Treviso pack, led by Valerio Bernabò, was tempered by a near first-team backline and they did well to stay in touch with the league leaders until 18 minutes to go.
With the score at 14-8 to Leinster, Richardt Strauss crossed after a break by Fionn Carr and the floodgates opened.
Leinster ran in three more tries with Nacewa's coming in the 66th minute. He was replaced with five minutes to go - his last telling action being to set up scrum-half John Cooney in the 72nd minute.
Schmidt's troops have now won their last 11 matches and are 14 points clear of the second-placed Ospreys ahead of their game in Edinburgh tonight.
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