Before the patch Check out a version before this patch (e.g. " git checkout dc437b51715 ") Go to admin > development > debugging and turn perfdebug on. Or if using MDK: " mdk run mindev " Create a test course that includes at least 10 participants Create an assignment with "File submissions" enabled in the "Submission types" section Enter the assignment and hit the "View all submissions" link to view the grading page. Use the "edit" -> "edit submission" link on a number of students and add a file to their submission - (5 students is probably enough for testing, but the larger the number of students the bigger difference in sql reads that will occur.) Reload the assignment grading page about two times. Take note of the "DB reads" value at the bottom of the page. Apply the patch Check out the version with this patch applied. Reload the assignment grading page a couple of times. Take note of the DB reads value at the bottom of the page. Confirm that they are lower than the number before the patch.