From the test we’ve received so far, there is concerns with the Level 3 Chicago peering node. starting here that we’ll want to look into:
7 234 ms 214 ms 223 ms BLIZZARD-EN.ear7.Chicago2.Level3. net [4.7.196.134]
8 226 ms 295 ms 276 ms ae1-br01-eqch2.as57976. net [137.221.69.33]
These peering issues can take some time to resolve, but we appreciate your patience and reports on the high latency issues in World of WarCraft. We’re getting everything gathered and inputted on our end that you all have provided so far.
If those impacted by the issue, could you include a WinMTR test while running the game for 10-15 minutes? This is a more detailed test to show us details about the latency and packet loss occurring to our servers.
Hopefully, we’ll have more information on this soon 
Thanks for your continued reports!