Hi @amy_tracy_wells
When I want to do this, I open up two web browser windows side-by-side and launch speedgrader in each; it works pretty well. The only issue I have is speedgrader doesn't auto-update as you submit grades, you have to refresh the page to see changes. So, it can be confusing as to which students you have graded and which still need grading. I just refresh the page after I submit each grade.
Another tip, I will sometimes read through the submissions and find a response that exemplifies a good answer, then copy paste it into Word so I have a reference as to what I'm looking for in a full response.