Due to the nature of select2.js, users are able to enter multiple sort options, which is entirely useless since the probability of having a tie to break is near zero. In the future, perhaps it would be worth resolving this minor issue.

Looks promising, but the sort option seems to be broken on the Best Submissions tab:

Sorting seems to be going in descending order on the All submissions tab, not sure if that's intended?

I believe it appeared to be sorted that way due to the Best Solution tab overriding the sorting options with runtime ascending. I have changed this and added ascending and descending sorting options for memory and runtime. In the future, perhaps a sorting option for submission source size could be added.