The perfect low-load time to do something like that would be upon submission, before the link is shown to anyone. Also it's a good time to make sure it's not a

The perfect low-load time to do something like that would be upon submission, before the link is shown to anyone. Also it's a good time to make sure it's not a 404 or 500. I think the titles are manually changed, because plenty of times descriptive titles are left intact.