Humm. . . that is an interesting one. It’s hard to say without more info though, can you please post your entire dmesg so we can see what init is running right before and after that point? Might help zero in a bit more.
Are you using the default, desktop or Xen kernel? Tried it with apci turned off as a boot argument?
rtc0 is the /dev entry for the realtime clock. See ‘man rtc’ for more info.
And some googling and LewisWithTheLongName’s post gives us a hint: AFAICS your problem is solved by replacing the installed kernel-desktop by kernel-default.
So it sounds like passing the acpi=off boot argument corrected the issue then is that right? It’s starting up without undue delays now? If trouble persists go ahead an post in the full dmesg, or pastebin it, etc.