This is a good point. For my application, it does an update of the statistics every day at midnight UTC. I've modified it now so that it does one user every 15 seconds instead of just doing them all as fast as possible. That means for 40 users, it could take up to 10 minutes to update all the days statistics, but that really is not a big deal.

Also, I wouldn't mind running the statistics update at a different time, say to coincide with a "low period" for the server - if such a time exists in such an international site... is there a better time of the day to run statistics updates or does it really not matter that much?

This is a good point. For my application, it does an update of the statistics every day at midnight UTC. I've modified it now so that it does one user every 15 seconds instead of just doing them all as fast as possible. That means for 40 users, it could take up to 10 minutes to update all the days statistics, but that really is not a big deal.

Also, I wouldn't mind running the statistics update at a different time, say to coincide with a "low period" for the server - if such a time exists in such an international site... is there a better time of the day to run statistics updates or does it really not matter that much?