Consistent Lag issues on MP server without the same lag issues

Before i DL'd the Newest version of Minecraft, Everything played fine, Occasional Lag, but nothing worth note.
Then after Dl'ing 1.4.2 I began to experiencing Severe lag. My regular FPS is around 30-40 FPS, when the lagspike hits (Around EVERY 10 mins)I get driven down to between 0-3 FPS. and like I said, It's every 10 min that this happens! I have talked to the Server owner, but no one else is getting this consistent Lagspike problem. I will be deleting and re-downloading Minecraft to see if that may be the issue, and I have checked my Internet connectivity, but no problems have been reported there.