I’m not sure what people are meaning by the terms “slowness” and “action” here, to be honest. If “action” is people rushing the barricades on the stairs, then I’d be bored if it was all stuff like that. I find that sort of thing “slow”.
I’ll put up with fight scenes if they’re part of a narrative. But not if they’re like the one Lord of the Rings film I saw when I was babysitting the now grownup kids of friends. It was 20 minutes of battle scene before I went and got a book.
Action - if it means chase sequences, fight scenes, explosions - bores me.
If “slowness” means long, contemplative takes with no dialogue or narrative, then there isn’t any of that in Silo that I’ve noticed.