The Jags recorded their second win of the campaign over Jim Jefferies' side to give themselves a three-point cushion in the promotion race and move seven points clear of third-placed Morton.
In front of a vocal 5,268 crowd at Firhill, a Steven Lawless double and goals from Conrad Balatoni, Stephen O'Donnell and Ross Forbes handed McNamara's men an eye-catching victory as they reclaimed top spot in style.
The Thistle boss said: "I thought it was a fantastic day all round – the fans, the atmosphere, the performance and the goals we scored.
"I thought we started the game really well and got the goal then Dunfermline came into it a bit and got the equaliser.
"We were outstanding to a man, every one of our players.
"Even at 3-1 and 4-1, they still wanted to be positive and they had the energy to keep going.
"It always helps when you are up, everyone gets confidence and wants the ball. I am delighted. It was a great day for the club.
"I think it is up there with our best performances of the season. You look at the Airdrie game when everything went for us and we scored seven goals.
"The support gives everybody a lift. Credit to Dunfermline, they brought a good crowd with them as well and it adds to the atmosphere. I said to the players before they went out that is what they want to play against. It was a great atmosphere for them to go and show their ability."
Despite Aaron Muirhead giving Dunfermline a lifeline as he inadvertently knocked Ryan Wallace's cross into his own net to cancel out the opener from Lawless, the result was never in doubt as the Jags pulled away in superb fashion.
A thunderous strike from Forbes early in the second half made it 4-1 and clinched the points. McNamara hopes he will be able to hold on to the former Motherwell youngster beyond the end of his short-term deal.
He said: "I have got to give a special mention to Ross Forbes, the lad has been fantastic since he has been here.
"He is one I would really like to get tied up for a while. He is signed until January and is playing for appearance money.
"He has a desire to play football and a lot of ability. I would love to tie him up for longer."
The only concern for McNamara was a late injury to keeper Scott Fox, with the Jags No.1 replaced by Ryan Scully and expected to be ruled out for up to eight weeks after tearing a thigh muscle.
Another note of interest was the surprise return to action for Mark McGuigan, with the striker recalled early fro m his loan spell with Albion Rovers.
McNamara said: "He has still been training with us and looked good. He scored a few goals for Albion Rovers. My thought to get him there was to get him confidence and games and get him scoring goals.
"Albion Rovers aren't too happy that we brought him back early, but with Steven Craig out [on Saturday] and next week as well, I thought it was important."