I ran with a 4090, everything maxed out, and even with DLSS off it never got anywhere near that low. With DLSS on, I was seeing about 80-100fps when stuff is casual and when there's a lot going on down to 60 or ever so slightly below (probably the lowest I saw, in the biggest fights, was about 54). This was before the official Nvidia Driver update for the game, also, which dropped today. No idea how much that'll improve stuff.
Most of it is CPU bound, though. There's a lot of calculations going on to keep the various AI elements and stuff of the open world turning in a 'natural' way. Like, the frame rate gets crunchy when there's a lot going on - but it's more about there being a lot of actors than it is about loads being rendered. So it's a CPU bottleneck, not a GPU bottleneck.