Cron definitely should not be taking 2.5 hours. The recommendation in modern Moodle versions is to have cron run every minute or so (and therefore each cron run should only last under a minute, and do a bit of work).
So, it is not that cron is being slow to close overdue quiz attempts. It is that cron is busy doing other stuff, and so does not get around to processing quiz attempts.
Anyway, this bad cron performance is something your server admins probably want to get to the bottom of.
In the logs you copied above, only the "Looking for quiz overdue quiz attempts..." bit is relevant - but it is part of a whole lot of processing related to the quiz, which it total took used 2.0344040393829 seconds. So, the quiz is not your problem. Once you sort out whatever is the problem with cron, then your quiz attempts will be closed punctually.
So, it is not that cron is being slow to close overdue quiz attempts. It is that cron is busy doing other stuff, and so does not get around to processing quiz attempts.
Anyway, this bad cron performance is something your server admins probably want to get to the bottom of.
In the logs you copied above, only the "Looking for quiz overdue quiz attempts..." bit is relevant - but it is part of a whole lot of processing related to the quiz, which it total took used 2.0344040393829 seconds. So, the quiz is not your problem. Once you sort out whatever is the problem with cron, then your quiz attempts will be closed punctually.