Gradebook

I'm working on a project for middle schools where we have many students (right now 275+) in a single course to access content and take some quizzes.  I'm finding that I can no longer open the gradebook as the UI times out.  If I do get in and I need to add a new grade category when I save the category I'm back in this boat after I click 'save.'

I increased the PHP timeout to 4 minutes (up from 2 minutes).  That gives me more time before I get the timeout error!  After maybe 10 minutes if I re-try in the same session (after MySQL processes have completed) I get in.  Taking 10 minutes per gradebook update/save is too long.

I can see in the MySQL process list that it's going through and doing various processes like

                           SET aggregationstatus = 'used',

                               aggregationweight = 0.021276595744681

                         WHERE itemid = '122' AND userid = '385'

and others after the UI times out.  Once these all complete I can get in in the same session.

We're running Moodle 2.9.2+ (Build: 20151016).

This only became a problem recently as I've added more students to course.

Is there anything I should turn off or can turn off to prevent this recalc from happening all the time?  Are there tricks for large courses?

thanks,

-- Scott