What the reason for 6 FPS in "that Atlus game" with ~60% CPU & ~34% GPU utilization?

That's really odd. Please, tell me what version exactly you use to have 19 FPS in casino, so I test it instead of random ones prior April.

I've been playing "that game" (not sure if we need to keep calling it like this since the forum is full of threads fully naming it) for months and all versions I've used prior to April gave the same results. It might be your graphics card that makes the difference. I am not familiar with yours so I have no clue if it's better or worse than mine (a GTX1050TI).

Leave everything at default settings and change only SPU to LLVM (still called "experimental" in versions prior to April) and set graphics renderer to Vulkan.