fps getting lower and lower every game unless i close the client

guys im starting to lose my mind with this bug.. every game the client gets more and more laggy, the problem is that it effects the game also.. my fps goes from 200 to 160 to 120 to 90 to 70 to 50 to 30(every game it gets worse by about 20 fps basicly).. the screen starts to flicker.. if i alt tab and close the client everything is going back to normal i get high fps and the screen doesn't flicker. i tried low spec mod and close client while game is running, they dont help. only complete shut down of the client.. the only solution i have for this is to restart the computer which again gives me like 2-4 playable games and then its unplayable again.. please if some one have that bug or knows what to do please help

btw i posted a ticket about this.. i tried all the basic stuff of upgrading my drivers and restoring default settings of the gpu and reinstalling.. nothing works