the anti alias does not have to do with the display of the thickness of the lines, but with the definition of the tract when they are inclined.
at least to me changing the status of the option does not change the thickness of the line.
could be a question of video card, some pattern setting, of an option of the system I do not remember, of other; I asked a file with a banal sketch just to verify that opening it shows or not the same situation and then exclude hypotheses.
but of course if it is a slam to pass from one pc to another for those who ask questions (conscious of the fact that the image could not be good enough to understand the problem) I look good to stress them over.