I check mine and found :
0 -> 9s for initramfs to kernel boot
9s -> 44s boot until kdm ready to log in (35s)
44s -> 1m52 to have KDE ready to use (which looks huge time 1m and 8s !)
I think there are too much modules loaded on initramfs and I should find time to build a small one !
There should be some way to shorten kernel boot to login screen but I cant find a way to trace boot.
Bootchart is available on gentoo and not sabayon
My /var/log/boot.log is empty do you get the same empty file ?
For KDE I tried to logout login and then login time drop to 17s ... I think I should cleanup some .kde4 files.
Having start => kdm login ready of 30s looks good timing and then KDE or GNOME login should not exceed 30s.