Firecracker says this about performance in their specification:
It takes <= 125 ms to go from receiving the Firecracker InstanceStart API call to the start of the Linux guest user-space /sbin/init process.
So far I’ve been using Firecracker to start relatively large VMs – Ubuntu VMs running systemd as an init system – and it takes maybe 2-3 seconds for them to boot. I haven’t been measuring that closely because honestly 5 seconds is fast enough and I don’t mind too much about an extra 200ms either way.
That’s pretty fast. Click through for more info on installation and configuration.