The whole kernel discussion seems to be a red herring. The reason the android device was so slow is because the DHCP server timed out twice on a DHCP request. Those two timeouts caused 10s of the 11s delay.
I think there probably was something wrong with the DHCP server configuration.
It timed out because it wasn't there, not because it was misconfigured. The tablet was revalidating its previous lease, which was from a different network - so it was sending the request to the previously-known server address.
I think there probably was something wrong with the DHCP server configuration.