I'm not sure how to reproduce it, but during multiplayer matches the game will occasionally grind to a halt.
The same multiplayer match between the same two players using the same two ships worked perfectly fine for two games, but for some reason during the third one the game slowed to around 5-10 seconds per frame (yeah, per frame) for half a minute, before degrading to the point where there were about 45 seconds to several minutes between frames.
Not exactly the same issue but both mouse and keyboard input seem to happen on the same thread as rendering, which means that even in moderate frame rate slowdowns typing into the MP chat box is hell.
Yeah, it's all on a single thread for simplicity's sake. So it could be the games slowing down, but it's more likely it's the server being useless. sigh
What kind of battle size does it happen for? Does it ever happen in small battles?
I can't say with certainty but my impression is that it happens more often with larger battles. That could just be human bias though associating lag with more/bigger ships.
It has happened to me though in battles between two 10000k ships, and in 5000k battles between groups of ships.
The last time this happened:
I have a 2.6 GHz Quad-core AMD CPU
It only seems to happen in multiplayer.