City had not beaten the Cobblers since 1984, but an own goal by Northampton goalkeeper Lee Nicholls and second-half goals from Jamie Cureton and Jake Gosling sealed a second win following Tuesday's triumph over Port Vale.
However, Tisdale's focus immediately turned to Wednesday's trip to Bristol Rovers, where a win for Exeter could take them into the automatic promotion spots.
"We were excellent," he said. "We have won the last two games and scored five goals. We played with one striker again and scored three goals, we played deep and won, so it is on to the next.
"It all counts for nothing because it is all about the next game and three points, whether it is at home or away. We will focus on that and go for it."
Gosling's stunning individual goal was the highlight in Exeter's win and saw the usually reserved Tisdale celebrate with delight on the touchline.
"It was the winning goal, that's why I enjoyed it," he said with Northampton looking their most dangerous at 2-0 down. "If it had been the opening goal, you wouldn't have seen a nerve move in me, I enjoyed it because it was the winning goal and today was all about winning the game, regardless of who scored.
"It was a terrific win and it is all about three points whether it is 3-0 or 1-0. It is hard to pick anyone out particularly. We defended very strongly. Northampton came very close to scoring and they put a lot of pressure on us."