I've had this problem for about a week, first I thought it's my internet, which is partely true, but every after fixing everything on my side the problem still pressists.
While playing Wotlk lorderon server I used to have 70ms, which is the same MS i get when I ping warmane.com.
For about a week I'm getting 600~1200ms, depending on hour (completly random everytime).
The strage thing is, when I go on MoP realm my ping is 70ms... I assume warmane is using the same SERVERS for all the different realm under their name.
so I'm very confused, my second guess was that something in my client is causing this... I redownloaded the whole thing, still the same problem.
Some pics:

Ping to warmane.com : http://i.imgur.com/UfZcpur.png
Latency on Lorderon (from same time as ping above) : http://i.imgur.com/ea8V9Pb.png
Latency on Warmane's MoP : http://i.imgur.com/gKjXGbs.png

In my eyes the only explanation for that would be that.. either me thinking that my ping against Warmane.com would be my ping ingame is wrong, or the Wotlk and MoP realms aren't on the same server?
I'm no expert, feel free to call me ******ed if I made a really stupid mistake :) help.