Red valve needed to be places only in places where one is missing, and for glass doors, try checking local inhabitants, they might have something useful
The game might load texture mipmaps into memory for the first 30 seconds when the level is loaded, also make sure you have the latest drivers for your GPU (the game runs on DX12) also try disabling any external Vsync if present in GeForce Experience
Did you install the UE4 prereqs in "Game folder/Engine/Extras/Redist/en-us/" ?
At what point of the game the issue occurred?
Have you tried tweaking graphical settings?
The game was developed on a rig with RX580 and run with stable 30FPS, the game is a bit demanding due to graphical fidelity, but shouldn't give this low of a framerate
