Comment 9 for bug 816035

Additional remark: I noticed slight differences in the kernel log regarding console mode initialization:

Console: colour dummy device 80x25 (when 1G)
vs.
Console: colour VGA+ 80x25 (when 2G).

When disabling the graphical terminal in GRUB (GRUB_TERMINAL=console), grub actually runs at normal speed again; but the subsequent OS startup process remains unchanged slow (probably because console mode is changed again). There appears to be some correlation between the presence of 2GB memory/dual channel access and the selected video mode; I however do not understand what is going at low level, possibly a bug in system BIOS. Can someone help or offer a workaround?