Here are some of mine:
1. For revised drafts, have students underline all changes made (for deletions and movement of information they comment about what they did in underlined text in square brackets). Then the two drafts are much easier to compare.
2. On grading rubric include a code for grammar comments. (Ex: CS = comma splice, RO= run on sentence, etc.)
3. To minimize redundancy with comments in essays and at the end of essays, place numbers in the margins and then at the end of the essay write the number and the related commentary.
Now give me some time saving tips because I have 2-3 preps and about 150-200 essays/month to comment on!