I found this to be an NA server wide problem - Cyrodiil, Wrothgar, Deshaan and Rivenspire. Not everyone was experiencing it so not sure if it is an Australian issue or what. My net connection was fine. This was a couple of hours ago.
Hi. It is normal to see lag after a new patch or DLC comes. Least it is for me anyway. The excesive lag is caused by eso players who return every 3 months. After each DLC is released. Once the DLC's are completed. The eso players who returned will then leave and comeback again after another 3 months.
Since ESO is catered to those players who comeback and leave again after they try new DLC's. In which case. One Tamerial is considered a new DLC. But free for all. Therefor. The lag will quit after 2 days or so. Once those who come back leaves again.
I not sure if this info helps. However I believe Cyrodiil is a different matter. We're on different Zone. I still get lag in dead campaign. But not as bad.