MAJOR FPS drops during monster-spawning content

Hello.

I'm looking for some insight on how to fix serious FPS issues I get during content that spawns monsters. This includes:

—Breach
—Strongboxes
—Hourglass events (Sanctum)

Nearby Shrines can also tank my FPS like crazy until I click them.

My specs are as follows:

AMD Ryzen 7 5800X 8-Core Processor 3.80 GHz
32.0 GB RAM
Windows 10 Home
NVIDIA GeForce GTX 1080 Ti

In-game settings:







Any insight on how to remedy this would be greatly appreciated. I'm unsure if this is a problem with my settings, GGG's optimization of a game that's obviously still in beta, or if my PC is just old.