Billy Zane says emotional acting can be just as difficult as high-flying physical stunts … arguing both take a toll on the body — so, performers need to be paid fairly for each.

The actor sat down for a recent conversation with Entertainment Weekly where he reflected on playing the title character in Lifetime’s “Devil on Campus: The Larry Ray Story” … and, he says portraying the convicted sex trafficker did a number on his psyche.

BZ says even playing a role — secondhand diving into the darkness — is a lot for actors … adding the body recognizes all the chemical reactions it’s going through, and it does affect you physically, so a few extra bucks ain’t outta line.

As for the old saying actors can’t judge their subjects … Zane’s kinda calling BS here — explaining it’s impossible not to judge such a guy like Larry, but that doesn’t mean he can’t understand the thoughts going through his head.

BTW … Billy says he also physically changed his body for the part — gaining a ton of weight to play Larry, and telling EW he pounded sugar to adds the extra pounds he needed.

If you don’t know … Larry Ray moved in with his daughter at Sarah Lawrence after getting out of prison — and, he was later accused of establishing a “sex cult” of her friends.