I have been having Tekkit lag for awhile now, so I decided to play on the vanilla server instead. When I got on, it was also lagging, but a different kind of lag. When I tried to chat, it took a few minutes for it to show up, but I saw it on the live map chat right away. It also took around a minute to open chests.

Does anyone have any idea what's going on? I've never had lag like this in a while. I have a fairly new PC that can run games which are more intensive than Minecraft.

EDIT: It seems that the longer I stay in an area the more the lag goes away. This would be fine if I didn't have to tp back and forth between spawn and my home.

Turn your internet off and on again? Always works for me.

its not the server its your internet that is all just check to see if restarting a;your router works and b; if restarting,your internet works also check to see if your internet cable or receiver is plugged into,ur computer fully.

-mega

Ah, ok. I will try that out.

Didn't seem to work. Everything else I do works alright, just not minecraft.

I have it occasionally, mostly after a few hours of play I start rubberbanding and blocks start reappearing. Only thing I can do is log off for a while and come back later. It might be a memory leak in the game itself, though such a thing should be nigh impossible to create in java as far as I understood =S

Maybe try "Force updating" to redownload the minecraft client in case theres a problem with your version?
Worth a try