I have that kind of Issue too and its not like staying the same over seasons. My recent case is between the last season and the current. Last season e.g cruicible and tower were the places where my fps were just halfed. This season cruicible & tower are working nice -5fps maybe but Gambit is a real pain in the ass. More than once i ran with around 20-30fps the whole game. Last season there was no problem at all. Battlegrounds is not stable abut ok its new :P