I just had to leave Ascalonian Catacombs explorable mode because of massive lag.
When fighting the first boss it got ridiculous and after THREE minutes of lag
I had to quit the game with Alt+F4, because i could not get into the menu anymore.
Yesterday i got the same lag spikes on another exploreable path.
I dont have lag anywhere else in the game. It seems that it just affects AC at the moment.
My FPS are stable and between 30-60.