Nostalrius Begins - Quality wow vanilla realm (1.12)

Doesn't matter what I'm doing, whether its a 40 man raid or solo questing in darkshore. Constant lag spikes of anywhere up to 5 seconds, makes it almost impossible to play.

I started noticing it about a week ago, before that had played fine for weeks on here.

It is only happening while playing Nostalrius, other games are unaffected.

Playing from Sydney, Australia.

Basically, have you changed something on your end regarding incoming traffic, because nothing has changed from my end to create this issue