Gotta disagree with your friend on this one lol. I found the middle part really dragged with all the side character stuff. The tension felt high at the start and end, but there was a long stretch where it just went flat for me. It needed to pick up the pace way sooner.
Totally get what your friend means. I was on the edge of my seat the whole time, especially during the factory scene and that weird dinner party. Even the quiet moments felt loaded, like something bad was about to happen. It just never gave you a chance to breathe.