[coreboot] Fast booting: coreboot versus optimized UEFI

Are there some hard numbers for coreboot initialization and bootloader
payload time (from power-up/reset to the start of the OS kernel load)?
Non-optimized UEFI starts up very slowly, in some cases slower than a
legacy BIOS, but some optimized UEFI frameworks start up quite quickly
and can begin booting within a few seconds of power on/reset.  However,
I suspect that even optimized UEFI is 2-3 slower than coreboot and a
bootloader payload.  Are there boards with both coreboot and UEFI
support where the respective boot times are compared and published on
the Internet?

Sincerely,

Ken Fuchs