The summer movie season has arrived — bringing with it the usual panoply of blockbusters, spectacular action and eye-popping visual effects. And, as always, supporting this groundswell of big-budget extravaganzas, such as this year’s “Solo: A Star Wars Story” and “Avengers: Infinity War,” is the specialized work of thousands of highly skilled visual effects artists and technicians.

But somewhat counterintuitively, even though many of these films are breaking box office records, the effects houses that create this magic are struggling.

“It’s an incredibly competitive industry,” explains Kelly Port, a visual effects supervisor at VFX house Digital Domain, who worked on “Infinity War.” “For as much money that’s spent on visual effects, it’s an incredibly low-margin business.”

That’s partly because state-of-the-art effects work is hugely labor-intensive; it can take a massive crew eight months to a year of full-time work to finish one film. Such a large investment of time and financial resources can be difficult to recoup because fierce competition for plum gigs on blockbusters drives prices way down.

When visual effects houses pitch the studios, they explain what they can offer and what it will cost. And of course, if a competitor is selling the same effects for a lower price, that firm is likely to be awarded the job. “Sometimes companies are so desperate for work that they’ll go lower than they think the work will actually cost,” Port says. “That hurts the industry. The margins are too thin already.”

The sheer volume of effects work being produced today would have been unimaginable 20 years ago. To put it in perspective, Port cites “Titanic,” which he worked on in 1997, when it was considered a cutting-edge blockbuster. The film had a total of about 300 VFX shots. “Infinity War,” by comparison, has more than 3,000 — a number that’s become an industry norm.

And it’s not just tentpoles. “Everyone can use visual effects now,” says Simon Stanley-Clamp, a visual effects supervisor at VFX studio Cinesite. “It used to be just the big shows. Now anyone from independent films to Netflix series has access to visual effects. They’re everywhere.”

More work means more workers: The field of VFX artistry has expanded enormously. “When I started in the ’90s, there were 300 effects artists, and you’d know all of them by name,” says Clamp. “Now there are 300 artists sitting here with me in this building.”

With margins so thin, timelines so tight and quality benchmarks so high, these artists are often under considerable pressure. Long hours and overtime are standard, especially when a release date looms and shots still need tinkering. “There’s an incredible push near the end of projects to get them out on time,” says Kyle McCulloch, a visual effects supervisor with Framestore who worked on “Thor: Ragnarok” and “Beauty and the Beast.” “We tend to be delivering shots right up until the final weeks before distribution. I’ve delivered shots with a week to go before a film hits theaters.”

Cutting it close is tough, McCulloch says, but necessary when studios demand it. That’s how shops like Framestore build and maintain their standing. “We trade on our reputation,” says McCulloch. “We have to be confident that we can deliver a large quantity of work at a high level of quality very quickly.”

It’s not up to individual companies, however, to handle all the effects on a single picture. There’s simply too much work to be done on an “Avengers” or “Star Wars,” and too much risk for the studio in putting all its visual effects eggs in one basket.

“Studios would be scared [to depend on a single VFX house] so they spread the big sequences across five or six different vendors,” says Stanley-Clamp. If one shop drops the ball or goes under — as Rhythm & Hues famously did after its Oscar win for 2012’s “Life of Pi” — the studio isn’t left scrambling for a last-minute replacement.

With the rise of big-budget cable shows like HBO’s “Game of Thrones” and high-end streaming series from the likes of Netflix, top-of-the-line visual effects are typical on the small screen. And over the past couple of years, TV shows have also begun to spread their demanding VFX work across multiple vendors.

“The TV side wasn’t always like this. … It’s gotten so big that it’s fractured,” says Luke Groves, a visual effects producer at effects studio Mr. X. “Companies like us have to take on more shows because we’re only doing small portions of each of them. That can be a tricky thing to manage.”

The result is a greater variety of work for artists, who often have to juggle three or four projects at once. That means VFX pros have less time to master the look of specific effects: Instead of working on a single show set in, say, outer space, a house like Mr. X might be working on one set in space, one in a jungle and one underwater, all with different effects and needs. “Where we would normally do one show, we now have to do portions of five unique shows,” Groves says. “It can be hard to deliver the highest-quality work across so many different projects.”

Still, Groves is quick to point out that there’s no downside to the company having a lot to do. Rather it’s a matter of “having to pivot to manage bite-sized portions of work and doing enough of it to fill budget caps.”

As the balancing act for VFX houses continues, things will only get harder for artists. “Shorter schedules but still at the highest quality possible; can we manage that much work under one roof at one time?” Groves asks.

There can really be only one answer.