A small H game shouldn't be this big of a problem.
Quite the contrary. AAA developers can usually afford artists that can work without many polygons (meaning the models are not as resource-intensive) and usually they'll pick shaders/effects according to the target hardware they want purchasing the game.
Indie devs usually can't afford to optimize much, the first model to pops out working is going to be used and they won't bother toning it down for certain hardware. And as for shaders/effects, they'll just pick whatever looks cool and add it in.
I have a 2080S and this game eats up 80% of it to maintain 60 FPS at 4K. It is quite heavy.
There might be mods for BepinEx that disable stuff, you could try to search for them. The shaders look quite expensive, and he seems to have added physics everywhere, which is also pretty expensive.
The dev seems to be targetting the Core i5-4590/970 GTX as recommended, so yeah, a 650M with a notebook CPU shouldn't cut it.