Have you called your ISP? could be on their end, they have had problems with WOW before (charter) in terms of shitty lag.
I don't think it's the servers because nobody i know including myself who has a shitty internet connection has been experiencing lag in the last few days. Could be on blizzard end but if it is again me and my friends haven't been experiencing it. You can have a 50mbps connection ,doesn't matter.
Just like the whole Comcast fiasco over wow a couple years back, i was running 25mbps and couldn't even play the game along with thousands of other comcast users, same thing happened with charter/wow.