Trollbane/Malfurion server has been having the lag issue in Zulduzar with warmode off for the last 2 days. Guild chat and general is full of people complaining about it. Feel free to pull the general chat logs to see when it starts and how many people are talking about being affected by it.
The shards with the issue are completely unplayable with 30+ second input lag on spells and NPC interactions. Just using a hearthstone or portal has a 50/50 chance in resulting in a disconnect.
I only see this problem in Zulduzar, and only with warmode off.