This is really obvious in retrospect, but I didn’t realize it until I saw it happen.
VMs boot faster than real hardware.
I have a proxmox machine and it’s really fast and it can shutdown and restart a vm in a few seconds, which I always marvel at. I initially chalked it up to being a fast machine but then one day I realized that a real piece of hardware has to go through the real bios boot process, find the boot disk, load the boot loader, run it load the OS from disk, run all the startup applications, and read all that from disk…
All that running on nvme is really fast, but if you do that in a vm, it’s running from page cache, and as I always say “NVMe is fast, but RAM is even faster.” so of course vms boot faster, all their disk (or at least lots of it) can be in memory when the vm boots, so it’s just shuffling memory pages around.