If you are experiencing excruciating slowness when booting up your Ubuntu powered device, you might find these tips helpful. My laptop is running Ubuntu 20.04. It takes about 4-5 minutes to boot-up the laptop. Which is quite abnormal for a laptop with 32 Gb of RAM. So I ran the following command,
$ systemd-analyze blame
What this gives is a list of startup applications sorted Z-A by boot-up time.
1min 5.974s mysql.service 51.281s docker.service 34.783s snapd.service 32.278s systemd-journal-flush.service 29.317s networkd-dispatcher.service 25.496s dev-sda2.device 22.545s snapd.seeded.service 19.878s accounts-daemon.service
As you can see for my laptop it was MySQL service and Docker service which was to blame for majority of the boot time. So I used the following command to stop those services from starting up at boot time.
sudo systemctl disable mysql
This improved my boot-up time by about 2 mins. And if you want to manually start a service again that was disabled, you can use the following command,
service mysql start
It's that simple. If this doesn't work you might want to look at reinstalling your ubuntu. Specially if you updated over the internet instead of a clean install when you updated your ubuntu version. Hope this helps.