I'm using a fresh install of VirtualBox 5.2.12 in a Windows 10 host, and installing guest Lubuntu 18.04 x64 with options 'minimal installation' and 'enable LVM'. The guest has 4GB RAM and 4 processors allocated, with a 100% execution cap and PAE/NX enabled.
It's running at a crawl, to the point where service startup always times out for some services, especially swap:
The guest is fully updated and running current guest additions. What could be causing this slowness?
I did two things that, together, fixed the issue: I decreased the allocated CPUs from 4 to 2, and I maximized the video RAM.