Goals from Tommy Rowe, Tyrone Barnett, Grant McCann, from the penalty spot, and Britt Assombalonga gave over 2,000 Posh fans plenty to cheer about as their team made it nine goals in five days, coming after their crushing 5-1 midweek Capital One Cup victory at Colchester.
Dean Leacock had opened the scoring for County in the first half, while substitute Yoann Arquin scored a late consolation penalty in a game which got away from the home side after a decent first period.
"I wouldn't say it was a great performance and I'm not happy with conceding two goals," said Ferguson.
"But I'm delighted with the start we've made - three games, three wins and 10 goals. You can't ask more than that.
"We've got periods in the game when we just go up a level, which is too much for teams at the moment."
For Notts County boss Chris Kiwomya it was a frustrating afternoon and he felt the game's key moments, including a clear penalty which was not given in the second half, did not go his side's way.
"I think there was a penalty there for us but we don't get it and then we concede a soft goal. They also get a penalty where I'm not sure if we catch him.
"Those are major turning points but overall I don't think we've done as well as we can do."
"We didn't get the ball in wide areas like we should have done, like what we did for the first goal."