Major FPS decrease when aiming camera to the ground.

Hey there,

I'm having a bit of a weird issue, whenever I aim the camera directly to the ground my framerates drop quite significantly.
As far as I can tell this it only seems to happen in La Noscea areas like Limsa Lominsa, Middle, Lower & Western La Noscea. [edited]

I recorded a small video to show what I am talking about:
https://www.youtube.com/watch?v=Tpfs75XlmjI

Here is some basic information about my system:
Windows 10 64-bit with the latest updates.
Intel Core i5-7500.
AMD Radeon RX 480 with the latest drivers (17.3.2)

[edit] It had something to do with Tessellation, taking it from High to Normal fixed the issue.