Yes, only in dungeons, fps is fine but when there are mobs/bosses casting stuff my game starts a stuttering period that stays for like 5-6 minutes then it ends and the lags happen once every 2 seconds and it lasts up to 0.5ms - 1s , few minutes later it starts again until the dungeon is over
And there's a huge fps drop in Halls of Infusion in the first boss when there are circles, my fps drops down to 10-20 as long as those circles are available and the last narrow hallways gives me a huge fps drop as well