I've encountered these problems quite regularly lately, I'm assuming that it's just the server acting up because the number of people allowed in a map has went to 160 - 300, causing much more problems then usual.
You could try redownloading, though I don't think it would do ya any good. To minimize the lag, shut off your view distance and water reflection. You could even try shutting off the name tags if the lag gets severely bad.
I hope it works out for you Hun! Let me know if there is any more problems!