A champion in F2 and FE, de Vries joined AlphaTauri after excelling last year in a one-off drive for Williams at Monza, where he finished ninth while deputising for Alex Albon.
Despite being an F1 rookie, De Vries' vast experience as a Mercedes test driver and a winner in other forms of motorsport made him an enticing prospect for AlphaTauri to replace Alpine-bound Pierre Gasly.
But the 28-year-old has so far struggled with the team's underperforming AT04 across the first five grands prix, punctuated by a spate of costly crashes and errors.
While reports that De Vries's future is already under threat are believed to be wide of the mark, the Dutchman nevertheless has to show improvement to stop the pressure from building.
According to seven-time grand prix winner Montoya, De Vries deserves more time after a tough run of street circuits, some of which De Vries had never raced at.
"It's not easy coming into F1, but I think he just needs a bit more time," Montoya told Motorsport.com.
"I think when he gets back to Europe, to the tracks he knows, I think it's going to get better for him.
"The schedule is difficult for him as well, coming to all these new tracks in the beginning of the year, so I think once we get back to the tracks he knows his performance should get better."
When asked if he thinks De Vries will be given that time, given F1's capricious nature and Red Bull chief Helmut Marko's notoriously tough approach, two-time Indy 500 winner Montoya replied: "I mean, that's the reality of the deal and part of F1, you've got to perform.
"But still, he has at least shown some signs of good performances, so we have to see a bit later on and give him a bit more time first."
De Vries and fellow rookie Logan Sargeant are the only drivers left without points heading into the European part of the season.
De Vries has outqualified team-mate Yuki Tsunoda just once and has yet to finish ahead of the Japanese driver, who claimed the Faenza team's only points with back-to-back 10th-place finishes in Australia and Azerbaijan.
