Life Hacks: Teacher Edition! Now that I've gotten your attention with that terrible title...

The Mathematical Association of America used to regularly run a column called Teaching Time Savers, an archive of which can be found here: http://www.maa.org/programs/faculty-and-departments/curriculum-department-guidelines-recommendations/teaching-and-learning/teaching-time-savers 

These articles offer tips on things like:


How to reduce time spent grading
How to influence students to study in a more effective manner
Advice for streamlining the writing of recommendation letters


Note that many (most?) of these tips are not specific to a mathematics course.

Are there any other collections of such articles floating around the web?
You will have to search inside it for which tactics affect time efficiency, but "Tools for Teaching" by Barbara Gross Davis is a great compendium of pedagogical techniques, with citations to the research which justifies them. The main focus is doing it better, not doing it faster, but an astute reader can for sure find useful tricks in there.