Hi there
The Vulkan API is prone to abuse if certain things are left open.
Vulkan in some cases offers direct MultiGPU support with your onboard VGA which is impossible because they are not bridged except for on newer computer. That the FPS drops between 200 and 30 can be because of a swapping that occurrs when there is the need to swap memory.
Usually it would be recommended to not only disable the Onboard VGA but to uninstall it and disable it in the BIOS
As of Februari 19 2024 Vulkan API remains at large due to compromised abuse of its API.