Open a terminal windows in linux and enter the following commands:
$ sudo apt-get purge snapd* <enter>
Above command removes snapd.
$ sudo systemd-analyze blame <enter>
Also, found the plymouth-quit-wait.service takes very long time in boot. To eliminate the problem, enter following commands:
$ sudo vi /etc/default/grub <enter>
# Insert below line:
GRUB_CMDLINE_LINUX_DEFAULT="noplymouth video=SVIDEO-1:d"
:wq
Update grub thereafter:
$ sudo update-grub <enter>