[mrob]

It takes about 2 seconds on my 8 year old desktop (2.5GHz Phenom II, SSD) running Debian unstable. 20 seconds seems excessively slow for your hardware. I wonder how long it would take to load in a Linux VM? That could eliminate the possibility of the hardware being a problem.

[jventura]

Thanks for your suggestion. So I've tested on a Xubuntu 16.04 installation on VirtualBox, and it takes 3-4 seconds to boot LibreOffice Writer. It has something to do with macOS X...