Mallinder also praised scrum-half Lee Dickson and Ryan Lamb after the victory.
He said: "It was a good performance today. We've been building towards that and we've had some good halves of rugby but I think today we were all round a good team in terms of our tempo and our attacking play."
In particular, he identified some superb defence, as his side resisted Quins while a man short in the second half.
"Defensively we shut them up and stopped them playing, which of course they are good at, so we're very pleased," he said.
Mallinder reserved special praise for his halves pairing of Dickson and Ryan Lamb, the latter kicking 13 points and providing a sublime pass for Roger Wilson to score the side's second try.
"Ryan was excellent. His decision making was outstanding; he's maturing rapidly and playing some good rugby.
"Lee's been very good for us and is actually getting better. He's been good for us for the last two or three years and I have described him as being the heartbeat of Northampton.
"We want to play a high tempo game, we want to get the ball away, and when you have players like Ryan Lamb as well and you have good runners running good angles that's how we want the game to be played."
Harlequins director of rugby Conor O'Shea, contemplating his side's second defeat of the season, admitted they had been out-muscled by Saints.
"They were just more physical than we were and they won the contact and collision area. They got momentum," he said.
"If you come here and don't get momentum then you're going to be in for a tough night. They were outstanding tonight and we weren't.
"For the first time this season there was an 80 minutes where we haven't actually performed, but that happens."
After a good start, Quins were undone during a crucial 10 minutes when Nick Easter was in the sin bin.
Saints shot out into an 11 point lead, which became 14 points just after Easter returned.
"We started the game pretty well but we didn't get any score and we offloaded when we shouldn't have, and we coughed the ball up," said O'Shea.
"They got the lead and gave the crowd and themselves a bit of a buffer to relax and play."
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