McCall celebrated his third anniversary in the role on Monday and watched his team begin the new year in style with a fifth consecutive Scottish Premiership victory, which kept them second in the table.
Ainsworth struck from 20 yards before substitute James McFadden scored from further out to round off a perfect start to 2014 for McCall, whose side hit the post through Stephen McManus, Ainsworth and Shaun Hutchinson.
McCall said: "I thought it was a fantastic performance. We keep reverting back to last season and the season before and the players we have lost, but I thought the second half was as good as we have been, on a par with anything.
"The football was terrific and we have created some fantastic chances. Bear in mind it was against a side who don't lose a lot of goals.
"It was a good game. St Johnstone could have scored a couple, they have hit the woodwork a couple of times and we hit it three or four times.
"We said it might not be a day for pretty passing but they passed it well and moved. I was really proud of the performance. I thought it was the perfect all-round way to start the new year. It was just a delight."
Ainsworth's goal was his fourth in as many games and McCall said the club were "quite near" to extending his loan spell from Rotherham, which ends after the visit of Inverness on Saturday.
McCall said: "I think we are going to have to pay him a little bit more than we were paying which is unfortunate and we probably haven't got it, but he has scored four in four so the money keeps going up.
"But we are hopeful. There was dialogue on Tuesday and hopefully it will be sorted in the next couple of days."
One loan which has come to an end is for Dundee goalkeeper Dan Twardzik, who initially stepped in for the injured Lee Hollis and Gunnar Nielsen but kept his place when the Faroes goalkeeper recovered.
McCall said: "He has been absolutely fantastic. His all-round game, everything he has done he has done terrifically well.
"Since he has come into the team we have won five. I'm sure he will have a great future in the game."
Meanwhile, Saints boss Tommy Wright was disappointed with his side's performance in either box after they saw the game slip away despite contributing to an action-packed contest.
Wright, whose team hit the post through Dave Mackay and Stevie May, said: "It's a strange game at times because it could have been 4-3 at half-time.
"We didn't start the game well, which was key. We let them get a good foothold in the game and the tempo they played at.
"We settled down and created enough chances in the first half to be level but we did contribute to our own downfall.
"The goals are poor from our point of view, ill-discipline and not dealing with one against ones, giving away soft free-kicks to a team that has good delivery.
"It could have been 6-4 to them because there were a lot of chances."