It must be more of a new issue then…and I say that because a couple years ago, I had 10 animal pens stacked on each other with 5 gold rocknose in each. Yes, I realize that is eons ago, but not once did the game lag out, or crash like you explained.
That all being said, since then, and since the nerf to pets and all the changes, I dont see the need for so many pens…but then again, I wont tell people how to play. If that many pens causes issues, then Funcom needs to address it - be it fixing the crashing issue or limiting pens.