We should clarify that. Our example is an OCP Winterfell node, where boot time went from 8 minutes to 20 seconds.

That's an edge case. Asserting that boot is typically 20 times faster is misleading.

It's pretty typical boot time for most UEFI server platforms with network cards and RAID controllers. The Dell R630 takes about six minutes, the HP DL3x0 is about eight and the Lenovo x3550 takes over ten. Of the ones I've tested only the Intel s2600wf is under two minutes in a stock configuration, but with LinuxBoot it is less than twenty seconds to a Unix shell despite the PEI and DXE serial debugging messages: https://www.youtube.com/watch?v=0HISDFXZvSI

Out of curiousity, what devices do you have that it takes 8 minutes for the DXE to initialize?