I set up an 18.04.2 LTS Ubuntu in VirtualBox version 6.0.10 r132072 (Qt5.6.3), and it is horribly slow. It feels like the refresh rate is around 2-3Hz somewhere.
8 logical CPU cores, 100% execution cap, 16GB RAM, PIIX3 chipset, 128MB video memory, 3D acceleration enabled on VBoxVGA, default paravirtualization interface.
Running on Mac OS X 10.14.5 host, 32GB RAM, i9-9880HQ 8-core hyperthreading, Radeon 560X.
Anyone with any idea on how to speed it up? ( I probably made a simple mistake somewhere, so shoot the most basic answers first )