Diablo II: Resurrected Graphics

Will Diablo 2: Resurrected be able to run smoothly on an average PC if during gameplay, graphics is always set to classic mode?
Or does the classic and modern graphics run at the same time, while only one of them is visible but both data runs through the CPU and/or GPU therefore the game runs the same no matter which graphics are currently visible?

I ask this because my desktop PC can run D2:R, but the family laptop probably would struggle with the modern graphics since it doesn’t even have a dedicated GPU (Diablo III can run on the laptop), so I thought if the graphics would be set to classic on the laptop all the time, it may not struggle, but it depends on the game’s coding how it handles the two graphical layers.

Yes I have seen the System Requirements, this question is about how much CPU/GPU power the game needs during gameplay if it is set only to classic and not modern graphics.