I got the libguestfs launch time down from 12 seconds to 9 seconds today, 25% faster!
It turns out that the appliance’s BIOS was waiting for 3 seconds for someone to hit [F12] on the imaginary keyboard. A simple patch to bochs BIOS fixes that … This patch benefits everyone using Fedora and virtualization, since all boot times will be reduced by 3 seconds.
This is only the start of the optimizations. I’m pretty certain we can get it down to a 4 or 5 second launch time.