My experience with SpeedGrader (as an instructor) is that moving from one student to the next is EXTREMELY slow. I am often grading 300+ quizzes at a time and grading by question to maintain consistency. Each time I grade a question it can take 4-5 seconds for the page to update after clicking the "Update" button to save the score changes and another 7-8 seconds to load when I click to the next student. This 11-13 seconds adds up to an hour of wasted time if I am grading 300 quizzes---and that is 1 hour per question. Generally I have to grade more than one question, so this is multiple hours wasted. And this doesn't account for the time spent scrolling up and down the page just to get to the "Update" button.
I wonder if it would be possible to have the browser download or cache the files for the next 5 or so students in the grading order each time a student's page is entered so that the page for the next student is being prepared while I am working on grading the current student.