Inefficiency during boot of linux guest
When a kubuntu guest (but probably any linux) boots, vboxadd is slowing down significantly the boot (generally top of the systemd-analyze blame).
The reason is probably that the setup() function in the vboxadd script always invokes 'depmod' even when there has been no change.
It seems that depmod should be invoked conditionally on what is done inside setup_modules(). In particular if there is no changes, it should not be invoked.
All that said, I do not know what I am talking about since I am a linux&vbox noob.