I've had this happen since patch 2.1. It went away after the hotfixes that came after but has since returned to a much greater degree since 2.16.

I find that it used to be related to instances but has since started crashing in open world zone as well. It's making it nearly impossible to complete anything.

I turned in a support ticket in-game and posted in a thread in this very forum over a month ago when it began being an issue. Sadly it's making it very difficult for me to play the game at all.