Don't slow down Ubuntu boot-up when no Ethernet cable is attached

Don't slow down boot-up when no Ethernet cable is attached

In Synaptic find and install the ifplugd package. After installing it, open a terminal and run this command

sudo gedit /etc/default/ifplugd

Edit the file by modify the lines INTERFACES="" and HOTPLUG_INTERFACES="" if no interfaces are listed or if the wrong interfaces are listed. You probably only want to test the hotplug status of the wired Ethernet connection, so the lines should read:

INTERFACES="eth0"
HOTPLUG_INTERFACES="eth0"

run this command then:
sudo gedit /etc/network/interfaces

comment the following line, if it exists:
auto eth0
I don't pretend to understand these options fully, so please post corrections if I'm wrong. I've also modified the ARGS= line to add the string -b which silences the otherwise excessive beeping when you plug or unplug the cable. Save the file and reboot.

Don't slow down boot-up by synchronizing with network time

Ubuntu pauses during boot-up while attempting to synchronize the system clock with a remote time server, but you probably aren't connected to the internet when you boot with a ThinkPad, so this attempt accomplishes nothing. . Eliminate this delay by opening a terminal and entering:

sudo chmod -x /etc/init.d/ntpdate
For more info, plz refer to here