[Gryphon]

About how many characters it updates at a time;

It actually updates the roster count divided by 70 and rounded up. If you have more than 70 people on the roster, it will do 2 at a time, if more than 140 it will do 3 at a time. It picks the oldest updated characters to fetch each run and it is scheduled to run about 140 times a day.

This can be improved a little bit, but for the most part, if you try and gather too many at once it just won't run on vBulletin's mock cron.

I have many mods I have created that do external data fetches like this mod, so I also run the vB Scheduled Tasks via try cron to ensure that it runs once a minute regardless of forum traffic. But I mainly do this because external data fetches are often slow and/or intensive so even if you had 1000 hits a minute on your site, vBulletin's mock cron just isn't powerful enough to execute properly.