If you are experiencing slower-than-expected loading of the Assignment View screen that appears when you open an assignment, it may be due to the size of your class. Every time this screen is loaded, all papers in that assignment are scanned for plagiarism. Extremely large classes (approaching 100 students) will take longer to process the assignment.
If this accurately describes your situation, you can resolve issue this by temporarily disabling the plagiarism detection while grading.
Click the menu icon
Select "Advanced Options"
Click to toggle the "Show Similarity Index feature" to the "Off" position
The Similarity Index feature allows you to quickly see if a student's submitted assignment is similar to any other student's submission for the assignment. For more information about how this feature works, please see the help article How can I check to see if a student plagiarized work from another student?.