Have NextCloud 13 Snap running on a Ubuntu 17.10 Virtual machine, VM is running on older hardware (Opteron G2) and using fairly slow HDD’s but still the performance is terrible, I created a sharing link just down and it took 24 seconds for the page to load once the link was clicked.
VM has 6gb ram and 4 cores - host node is mostly idle as it’s just a personal box.
following my experience, VM sometimes are nightmares when talking about perf.
For exemple, on my I7 system using Oracle VM, a debian 2 core is faster than a 4 core setup !
If using option sata controller + scsi controller in same VM, i loose around 50% of write speed…
VM are good to setup conf but forget about fine tune !
The disks and network are virtIO-Scsi and the hypervisor is proxmox (KVM) and is typically well supported by Linux Vm’s
unfortunately never used this.
Keep in mind that when you set 4 cores, the hypervisor must wait for 4 cores to be simultaneously free before giving that vm more processor time.
You may find that setting your vm to have 2 cores actually speeds it up quite a bit.