I don't think the BIOS-to-login time is a microbenchmark. Relationships
between micro- and "real" benchmarks is normally much more complicated
than in this case where the time you want to optimise is simply a sum of
the BIOS and the OS part.
I'd expect the BIOS time to be below 10 seconds in this case, so trimming
down the 27 second part is very relevant.
FWIW, which hardware vendors support coreboot well?
Datapoint: one of my *server* VMs takes 26 seconds from poweron to login.
P.S.: Am I the only one who thought that our editor was surfing a site
named "Rate Wives" -- until I got that it was the logo of a popular TV
show cut off? Another case of screen too narrow...