No one else is bringing up any kind of lag, so if you're having issues, it's most likely a client side issue or an issue with your ISP.
Double check your bandwidth, look in task manager (if you're on a PC), and see if you're getting high memory or processor usage from any processes other than Java. Try uninstalling then reinstalling Java, and if that fails, check your virus protection (if you have any), which has been known on a few rare occasions to slow down suspicious network activity.
~Jared