Okay this may be a one off thing, but it's worth reporting anyway.
During our Kongar kill (just..) a lot of the players but not all experienced heavy lag. Including myself.
As far as I know this was only for the Kongar fight and didn't happen anywhere else in Eldevin.
http://www.twitch.tv/benpezz/c/3712869
Check around 17:00-19:00 in that stream link, there's probably more but I skipped to the part where I moaned in the chat to save me watching through the whole thing to find the lag spots.
The lag was like nothing we've ever experienced. I was freezing up for about 3-4 seconds, my game was even making weird noises. I have a powerful PC and this was unexpected.
It caused one death for myself.