With so many moving parts and a lot of special effects, it's no surprise making Star Wars movies is hard work. However, the difficulty for Adam Driver comes from something else. His issue is that, as the current trilogy's big bad guy, he's got to be an intense villain, which is actually quite difficult on the set of Star Wars movies because things are actually quite light and fun in between takes. According to Driver...
Sometimes you have to be more focused in between scenes because what's happening is that, on something like Star Wars, it's pure comedy in between takes. It's stormtroopers running into walls because they can't see through their helmets.
Adam Driver is known for being an intense actor on the set, and while he doesn't really know where that comes from, he does admit that he likes to stay focused on his role while filming. He doesn't go all in for method acting but apparently does try to keep Kylo Ren at the forefront of his mind when making the Star Wars movies. This is all fine and good while the cameras are rolling, but it apparently, he tells Vulture, gets complicated once the director yells "cut" as things get a little less than serious.
One imagines Adam Driver standing off to one side looking stoic while a Stormtrooper walks into a wall right in front of him. Driver tries not to laugh out loud. He probably fails. It's a Saturday Night Live sketch in the making.
It's not all that shocking that the general mood on a Star Wars set is one of humor. Most everybody involved in the current crop of films grew up watching the original trilogy, making most people incredibly excited to be part of the franchise now. While there's certainly a responsibility involved, it also means that actors get to live out childhood dreams of swinging lightsabers and firing blasters. That has to be fun.
Whether or not Adam Driver is the only one trying to remain focused on his character in between takes, he's certainly one of the few that needs to be quite so serious all the time. Most of the rest of the actors could be allowed to have some fun without completely acting out of character. Not so much for the ball of raw anger that is Ben Solo. He's basically a walking temper tantrum. He pretty much hates everything and the idea of him even having fun for any reason is about the most implausible thing in the entire current Star Wars trilogy.
We'll get to see what angry Ben Solo is like in Star Wars Episode IX when the movie finally arrives to cap off the new trilogy in December of 2019.