So yeah, turns out the game's VRAM management is fucked. Even people with 8gb plus VRAM are experiencing the hiccups and stutters when running around. Someone submitted a note to the PC Gaming Wiki about it:
https://www.pcgamingwiki.com/wiki/Final_Fantasy_VII_Remake_Intergrade
Issues unresolved • Link[edit]
Heavy FPS drops • Link[edit]
The game can drop fps from 120 to bellow 30 fps when texture settings is set to high on a GPU with 8gb or less VRAM. This may be caused by bad VRAM management as the issue is solved by altering between low and high settings that will force a VRAM flush. A patch to fix this is expected but with no word from the developers about the issue at the time of this edit.
A video example:
Those always happen in the same areas, and are 100% reproduceable. Depending on the area, you can't go for a few steps without some sort of asset streaming or VRAM-related stutter.
Currently the only way to play the game (mostly) stutter-free is to use the 'Low' textures, which are equivalent to the original PS4 game's assets, and even then you'll still need at least 6gb of VRAM to be stutter-free, even with the 'Low' assets.
Only hope right now is that Square fixes the VRAM management via patch, but I doubt that'll happen... otherwise just gotta play the game with the PS4 settings. It's still a gorgeous game anyway, but I really wanted to use the new textures they made :/