In MDL-49332, emerrill raised time limits for final grades calculations. As we learnt at moodle.org, in a course with 7500 students and 70 graded activities, the memory may easily become problem, too.

This has significant impact as there is no way to add a graded activity to the course or access the gradebook, for example.

The full story of how we experienced this on moodle.org and how we tracked it down can be seen in MDLSITE-4750. Shortly, we needed to add raise_memory_limit(MEMORY_EXTRA); to grade_regrade_final_grades() to make the site usable again. It seems like reasonable step to have this in the core.