Force High Poly is an optional mod, not installed,
MakotoYuki90. Unless
ItzRobot installed it, it isn't the problem. It probably is the optimization, which is nowhere near as bad as AI Shoujo, but still not good, plus overloading on students.
ItzRobot Did you place more than the 23 students in class 2-2 and 5 students each in the other classes? Anything over that eats RAM like crazy.
MakotoYuki90 is correct that Kplug IS NOT the problem here. I've seen it stated that a full load of students, that's 98 while taking both the PC and the brown haired character, Ai's, automatically assigned desks into account, can take as much as or more than 32GB of RAM. The player and Ai, the girl who runs into the class late like a walking anime meme in the first scene in class, both take up a desk for story reasons. The worst part is the game barely touches the GPU.
Serance I've rarely had a problem and only JannieReplacer, before it was removed, and HCharacterAdjust or whatever it is called caused an issue. Out of those two, the only one that was an actual problem was JannieReplacer, the other was a shared key bind, which is easily fixed on the player's end.