I proctored my first exam yesterday and graded part of the paper stacks today. Proctoring was psychologically taxing for me, because I could feel the heavy concentration and some confusion and frustration in the air. And taking papers away from the students at the end was also difficult, because I had to be a meanie... :-P
One of the questions on the exam was on a fairly new topic that the students haven't had a graded homework problem on... and it stumped everyone except 2~3 whom I know are quick to get new concepts. The prof and I decided to make it a bonus question. He graded the harder problems and I did the easier ones. Definitely a more onerous process than grading homeworks.