Kubuntu 18.04 / KDE 5.12.6 - A few thoughts and things to do

[This post is a work in progress. I will add things until I change Linux version/distribution. Again]


1) KDE Desktop crashes when changing virtual destops. 
Apparently, the solution is to open System Setting > Desktop Behavior > Virtual Desktops > Switching and disable "Desktop Switching On-screes Display"

2) System enters stabdby on startup if the laptop lead is closed
I had that problem on OpenSuSE some yars ago. I thought it was solved years ago.
Edit the file /etc/systemd/login.conf and make sure you have the following uncommented lines:
HandleLidSwitch=ignore
HandleLidSwitchDocked=ignore

3) BlueTooth is always on by default
We SHOULD BE able to change the default value from BlueTooth interface. Well, in 2018, after so many years of developing operating systems, we are not. For me it's not working, but some said that the following worked:

Edit the file /etc/bluetooth/main.conf and make sure you have one of the following uncommented lines:
AutoEnable=false
InitiallyPowered = false

4) Prevent FPC/Lazarus from automatic updates
...Because it will be a mess.
sudo apt-mark hold fpc
sudo apt-mark hold fpc-src
sudo apt-mark hold lazarus



5) Speed up boot time
I managed to speed up boot time by doing the following:

a) Reduce the log history by limiting it to 5 days (not sure it is a good idea)
sudo journalctl --vacuum-time=5d

b) Delay the apt-daily.service which shouldn't run at startup. So...
sudo systemctl edit apt-daily.timer
...then paste this and save:
# apt-daily timer configuration override
[Timer]
OnBootSec=15min
OnUnitActiveSec=1d
AccuracySec=1h
RandomizedDelaySec=30min

Source: https://askubuntu.com/questions/800479/ubuntu-16-04-slow-boot-apt-daily-service