"We've raised the intensity and physicality, week on week."
The Springboks were only 14-0 up at half-time, thanks to centre Damien de Allende's maiden international try and a penalty try off a scrum.
But the second half saw South Africa score eight tries - including Habana's treble and more to Bismarck Du Plessis, Jesse Kriel, Lwazi Mvovo and two from Francois Louw - as they added 50 more points.
Radio Sport's Elliott Smith talks to Bryan Habana
"The first half we couldn't get going and made one or two errors, but the second-half performance was polished as I've been involved in with a Bok team," said Habana, a veteran of 114 Tests.
"As nice as it is to score tries, we can be really proud of our defensive effort," added Habana, who has helped French club Toulon win the last two European Cups.
"To allow only one try in three World Cup games was unbelievably exceptional."
South Africa now face a quarter-final with the losers of Saturday's Pool A clash between Australia and Wales and Habana said: "The hard work really starts now."
Habana could have beaten Lomu's record but, with 13 minutes left, botched what would have been his fourth try with a knock-on.
"Fluffing an opportunity to score a try at any time is never ideal," said Habana.
"If it was worth a lot more in terms of winning or losing a game I would have been a lot more disappointed, but again equalling Jonah Lomu's record is a truly humbling fact.
South Africa coach Heyneke Meyer added: "I am so proud of Bryan, as a player and human.
"He is a great ambassador for South Africa, has peaked at the right time and we need him."
South Africa captain Fourie du Preez, in the Springbok side when Habana made his Test debut in 2004, said the flyer's eye for the try-line had been apparent right from the start of his international career.
"Since Bryan's first appearance, he has been an unbelievable finisher. He is always in the right place at the right time," the scrum-half said.
Wednesday's match was the first time a team had failed to score at this World Cup but US coach Mike Tolkin, who made 12 changes, blamed a schedule which sees his side having to play Japan in their final pool match on Sunday.
"I am very frustrated and we are certainly not alone," he said. "It is hard to take when you have to make a line-up based on a few days rest and I am sure Rugby World Cup will look at this after the tournament."
- AFP
All time leading try-scorers at Rugby World Cup (active players in bold)
15-Jonah Lomu, New Zealand
15-Bryan Habana, South Africa
13-Doug Howlett, New Zealand
12-Drew Mitchell, Australia
11-Chris Latham, Australia
11-Joe Rokocoko, New Zealand
11-Rory Underwood, England
11-Vincent Clerc, France
10-David Campese, Australia
10-Brian Lima, Samoa
10-Shane Williams, Wales