Longest:
The Cure, 1996 -- over than two hours
I'd like to say the shortest I saw was XTC in Paris, when Andy Partridge quickly stop playing due to vomiting problems, but I was too young and too far away from the capital then
https://www.youtube.com/watch?v=5ZrCL1aF_Zg
Must be then Jay Reatard, 2009 -- about 40 minutes, for the same reasons you mentioned