However, after restart, everything login related is slow. The display manager takes 50s to start (with next to no CPU and HDD usage!), the same goes to XFCE start up, the same happens after hitting logout, it takes a really long time for the logout dialog to appear, only to see that I cannot restart, I cannot reboot (these two are greyed out), I cannot sleep nor hibernate (these two buttons aren't preset at all!). The same happens with lightdm as well as kdm, I haven't tried the others yet. Pointers to what might be wrong appreciated, as of now I have no idea whether it could be a config option or a bug and where :(
Thanks to all my kind readers' suggestions in advance. Most of other things (I tried claws and midori so far), works normal, so the system is at least usable when finally loaded.
After some more digging, I learned that polkit and upower services weren't running (they failed to start). Reinstalling the relevant packages fixed the issue:
# yum reinstall polkit\* upower