I have a thinkpad w540 k22100M whit this specs
Have windows 10 dual boot and there is no lag problem there but on linux the whole Xorg server lag. like its 1 second sometimes that the screen freeze. sometimes the cursor jumps in the terminal..
I have installed Nvidia 440. but when I run the live install from usb there is no lag. I tried different versions of Nvidia and also bumblebee.