yes everything i do gets lagged after i reach that amount of faces

My RAM speed is 3200 MHz and no, there is no humming of sorts in my case but there is a delayed reaction when i sculpt as well as move the vertices in edit mode

thanks for the responses guys, I actually meant 4 million and not 400k. In my case blender runs really smooth until the 4 million mark, Then things started to react really slower. By the way I have seen people sculpt in a really high poly count doing much more complex projects

Thanks for taking time to help me guys I tried it and did'nt seems to work for me,eventually I found this video youtube.com/watch?v=oecXkpAoq9U and corrected my shadow terminator and now it works fine