Massive LAG using a minion build in Act 3 made it unplayable

I was reporting this in the main thread about performance issues but i think this warrant a thread due to how i had to cancel going further with my Witch : using as minions half a dozen Skeletons plus fourteen Bone Constructs i encountered lag so bad the action was freezing completely and then moving at fast speed to compensate with the earlier massive lag ( i was in the Area with the Silverback Gorilla boss ) . I tried to customize every Graphics Settings i could think of but nothing worked . By default i play with settings that give ~80 FPS when there's no much action going on so usually the framerate remains playable 99% of the time , still for the game to crash that bad there is a serious issue going on here .

On a related note , my main character ( a Monk ) encountered twice such lag with the same Graphic Settings as i had with the witch . No lag on Breaching in Endgame and the Leviathan Area was very much playable in Act 2 for example so i don't think this Witch issue is related to the number of mobs on screen . Both of time the game massively lagged with my Monk was in the same Trial of Sekema room : the room where you have to survive during a timed battle against with big Pot ennemies that throw clouds of "insects" at you ( first time i got killed due to the enormous lag occuring ) .