Autolab running slower than before

[jhs-panda]

Noticed by many TAs, an issue for both students and instructors.
Viewing submissions takes much longer to load than it should. When grading assignments, TAs noticed that it takes a while for submission to load from view submissions page and when clicking from one submission to the next.

[20wildmanj]

Do profiling of submissions view / actions to see which parts of the logic take up most time
verify if code diff is making a meaningful difference in rendering