Zone clearing was going fine until we started clearing the trash going up to Pardas Predd's room. That's when the lag and crashing started. Didn't have this problem Friday night in a PUG raid, but a friend on Crushbone warned me it was happening in their raid, and like 10 minutes later, it started happening on our raid on Unrest.
I heard about that! Basically something about the adds on the staircase to Pardas just froze all combat in the zone and 5-10 second delays on movement and chat. People could still move around, just not fight the mobs at all: enemies froze in place, could cast but spells did nothing, could not auto attack.