check ram usage if you are running out of ram due to some recent addition that could be why
but also check your game settings
if you have vsync on or not
and also check if updating or unupdating drivers changes it
i had big laggy buggy when i installed mws but I survived via rolling back my nvidia driver and turning vsync on
still think i might also be running out of ram though so am planning to increase ram on my computer
have rather new computer too and i don't have anything besides the game that could eat ram but it be eating a lot with all the packs
also i feel like new packs are eating more than their share but that i cannot prove i just know that moment i open tartosa and view the sky its a death wish
maybe my computer is vampire too