The 23 year old from Bangkok, named 'Thai of the Year' after finishing the season ranked 16th in the world, displayed the ruthless form that took him up 110 places in the world rankings last year.
Paradorn, runner-up here last year to Argentine Guillermo Canas, won titles at Stockholm and Long Island in 2002 and recorded victories over six top 10 players including world number one Lleyton Hewitt.
"It's always tough in the first tournament of the year. I'm really happy with the way I'm playing," he said after winning his tie in just over an hour.
"I played much better today than in my first match. It's great to keep rolling along."
Argentine Juan Ignacio Chela, the fourth seed, went through after Croatia's Zeljko Krajan conceded during the final set after suffering a hip strain.
Chela, ranked 23rd in the world, battled back after losing the first set and was 2-0 up in the decider when Krajan said he could not continue.
Paradorn broke Van Lottum twice in the first set and then relied on his big serve-and-volley game to get the decisive break in the ninth game of the second.
He will next play Armenia's Sargis Sargsian, who beat eighth seed Albert Montanes of Spain 6-4, 6-3.
"I don't think I've ever played him (Sargsian) before but he's a good player who's been around on the tour for a while. It's going to be tough," Paradorn said.
German qualifier Tomas Behrend kept his winning run going when he beat Spaniard Albert Portas 7-6, 6-1 to reach the last eight.
Behrend, who plays mainly on the Challenger Circuit, had beaten Romania's fifth seed Andrei Pavel in the first round.
Australian Todd Woodbridge and India's Mahesh Bhupathi, hailed as the doubles 'dream team' by tournament organisers, were made to fight hard by Australian Mark Philippoussis and American Justin Gimelstob for their 4-6, 6-3, 6-2 opening win.
Woodbridge and Bhupathi have 100 titles between them but are playing the rest of the year with different partners.
Woodbridge is teaming up with Swede Jonas Bjorkman while Bhupathi will play with Australia's Joshua Eagle.
"We knew today would be tough," Woodbridge said. "This is the toughest match you can get first up in the season."
Philippoussis, a former US Open singles runner-up in 1998, is making a comeback from a career-threatening knee injury after a four-month layoff.
