If it's straight Ubuntu 12.04 (vs. Kubuntu, Lubuntu or Xubuntu), try disabling the Ubuntu One and deja-dup services (unless you really want those). Of course, that might disable Ubuntu's software market (I don't know, I don't use that), but you can install synaptic, which is arguably a better package manager. I have heard people complaining about Ubuntu One hogging bandwidth somewhat severely.
Another thing to try is disabling IPv6 support (if you're not using that) .
If neither one is it, let us know.