my fps is at about 20% what it used to be before spring update, but i also updated nvidia game ready driver to 364.72 around same time. never had problem with auto update generic drivers, in the past, on this pc which is about 3 yrs old. if i alt-tab out of game and back in i go from 15-18 fps to 80+ but i must do it every time i switch maps.
my pc
os win 8.1
intel core i-7 3770k cpu@3.50 ghz
16 gb ram
ge force gtx 660ti x 2