It appears they're proxying your wow data stream to get around bad/long routing issues, from what I can tell by a quick search and read of their FAQ. If the TCPAckFrequency fix doesn't work for you, I'd be very wary of any service that claims to make the interwebs faster by monkeying with your routes or anything else without telling you exactly what they're doing.

Maybe I'm being paranoid but it IS the internet, after all...