I have the same problem.
Same here everytime I turn on PC, I must do check files on steam and it always shows me I have 81 damaged files and they will be downloaded again. Otherwise game is unplayable I have insane fps drop durning game play screen freezes for 2-3 sec. Something is wrong with game files.
i have this problem for 4 now and i change every part of my pc and the problem still.