Back when I was running OpenACS 4.x on Solaris, I used to see AOLserver startup take a quite a long time due to very slow XML parsing of the xql files. But even that was only 1 or 2 minutes worst case, and when we moved the site to Linux (and much faster Intel hardware) everything sped up immensely.
Does the pause in the AOLserver startup happen consistently every time at the same place in the AOLserver log? Or was it a one time only or variable thing?
Note that the 16:48:00 line is probably the first line logged after whatever was blocking things went away. (You would have to confirm that by looking at exactly when the ns_log statements happen in the code though.) So the thing to do is look at the log lines immediately before and after the gap, and figure out what was going on during the gap. Presumably, whatever AOLserver was trying to do during that gap is what's responsible for the god-awful 5 minute slowdown.
The users-selection package is in contrib, so probably not many people use it and perhaps it is at fault.