Well, I've resorted to using the Low Quality test stream, never had ANY lags so far, and afterwards I watched the VODs of the best games with a quality that is higher than the quality of the HQ livestream (HQ VODs have 750 and HQ livestream has 500 if i remember correctly, maybe someone else knows more ^^).
I suggest you do the same, I don't expect a really quick change, as I don't think the cause for it can be so easily found and even more important, changed in the next few days (until season 3 starts).

Edit: Has someone done some traceroute checking to the stream to find out which route the packets are taking? I've only checked for the Korean Battle.Net servers so far, and surprisingly, the route was EU > NA > KR > NA > EU, if it's the same for gomtv I could see why we're having more lags than our American fellows :o