The worst situation isn't when you have a slow computer...its when someone in your LAN party has a slow computer, and everyone else is fine...it's in these situations where lag seems to reach a whole new level...
Weird things like damage being delayed for minute +, sound/graphic effects for weapons and abilities not appearing, etc...
Had a game where my fleet was sitting just outside the range of a Transcencia's meteor storm...problem is, one of my ships for whatever reason got in range while forming up which allowed the guy to target my entire fleet (range of ability and range of buff are two totally different things)...I'm sitting there for 2-3 minutes watching my fleet while managing construction from the empire tree when suddenly a 1/3 of my ships just disappeared...literally, just gone...I had no idea what was going on but I got the hell out of there as fast as I could...
As I found out after the game, apparently the guy had hit my fleet with meteor storm 4 or 5 times...yet, I didn't see any effects and didn't see any damage until it was already too late...it was weird as could be, some of my ships had no damage while some just disappeared...even weirder, some ships had hull damage but had a lot of shields left (I didn't have a prog so how that happened is beyond me)...