How about simply because the LinuxBIOS code:
1. Runs 32-bit instead of 16-bit code.
(I remember a 2x improvement rule-of-thumb).
2. Runs at full clock rate.
(Quite a difference between 6 and 600 Mhz - if different).
3. Enables the CPU cache.
(Could be another 10x or better factor there).
Not that I know exactly what your typical OEM BIOS does... :)
I'll bet the about pretty much covers the difference.
From: Eric W. Biederman
> I have wondered for the longest while why linuxBIOS can so easily be
> faster than the legacy BIOS's. And I have come up with an interesting
> hypothesis. Other BIOSs are obfuscated to prevent reverse
> engineering, and to hide their secrets. My only guess is this tangled
> up code slows them down.
