Have you rebooted the system since the upgrade? The apport file includes errors which would indicate that the versions of NetworkManager mismatch, which is indicative of an upgrade issue.
You might want to try to apply all available updates again using upgrade-manager. If you're still experiencing issues, please attach /var/log/syslog from a session where you see slowdowns, along with the output of the following commands: nmcli con status cat /run/nm-dns-dnsmasq.conf cat /etc/resolv.conf ps -ef | grep dnsmasq ** Changed in: network-manager (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1016080 Title: slow wired connectivity after upgrade to 12.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1016080/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs