--Please note that the following may be caused by Java 7, Update 5. It suffers from extreme stupidity and glitches, mainly stupidity; also note that this is the first time it has happened.
1)My messages will lag, taking up to 30 secs to be sent.
2)Just a couple minutes ago, the chunks were not loading, causing me to stand on plain air. This proceeded for about 20-30 seconds.
The server memory is maxed out right now so _EVERYTHING_ Will be slow. I can't reset it because there are players on and I don't have time to login and tell them to get off.
If you see these issues when connected to the server you can run /servermem in the chat bar to see what the server's memory is. Anything up near 99% is bad.