You seem the entirely be missing the point about the main issue of the GPU utilization increasing under this unusual circumstance of opening your inventory or interacting with a vendor and threading other problems into it
You and LordShar below seem to conveniently ignore there’s a high quality character being rendered in the inventory screen every time you open it, alongside the other in-game scene the video card is required to render. It’s the same quality character render that appears on the game’s main menu.
That is why the GPU utilization is going up.