Over the past couple of days I've been experiencing bad lag spikes in PvE, it doesn't matter what map. It's happened in Kourna during a turret defense, when there were only 3 of us. It happened on the bandit event in SW where you kill them to open the tunnel system - again, just two of us doing it although a squad of 31 was also on the map. It then happened while fighting the mordrem and then the beetle, for the beetle drop, with 3 of us at that fight.
I'm in NZ and I spoke with a friend who's in the USA and they have been getting it as well. Frames per second looks good, just instant-casts aren't.