Apparently someone once did a 15-hour continuous live organ performance of John Cage's ASLSP (As Slow As Possible).
http://articles.baltimoresun.com/2009-02-01/entertainment/0901300057_1_aslsp-john-cage-luchese
I wish I could see that.
The slowest performance I can find on youtube is like 20 minutes long.
@starkatt there's the six-hundred-odd year one currently playing that there's a live stream of iwrc
it's currently on a rest though, I think
@Felthry Yeah apparently it's a rest until 2020
@midi_mac yeah, I've seen a lot about that one :)
...okay even at 20min long it's pretty spooky.