Well, guess Emma will have to ask questions ... oh, well. Like OS ... got any tools on server? etc., etc.
However, did you check apache error logs?
What are the settings for PHP concerning time for a script to run and how much memory can be consumed.
That's a.lot of records and even from command line that process (if I re-call correctly) did take more than 30 seconds to execute ... even when accessing an OU deep down into the LDAP tree.
That's probably the other thing Emma would ask ... what are the settings for LDAP ... if set to top level .... somenet.net ... the script is having to sort through what it might consider junk ... printers, etc.
Do re-call this ... If not pointed to user internet schema in LDAP (an OU for users or whatever would get one to user internet schema), one got tons of accounts created for printers and other directory resources ... no firstnames, lastnames, email, etc. ... ie, to Moodle ... junk.
'spirit of sharing', Ken