I can try calling Blizzard, but I'm likely to get a pretty non-helpful answer like reinstall WoW or reset my UI. Worth a shot, however, so if I can get through to them we'll see. I'm definitely getting more "texture lag" than "latency lag" which seems to indicate a hardware problem. Like I mentioned before, the only puzzling thing is how it clears up as the night goes on, indicating to me that it is somehow linked to the internet connection, just not in an obvious way.