I was not at GUADEC, but thanks to the miracle of the InterWeb, I managed to see Federico's slides on his (wonderful!) GNOME performance work. However one statement intrigued me. "Slow performance breaks the flow (see Kathy Sierra's talk)."
Well, for me, the number one and two interruptions of my flow (and I suspect the flow of many others) is (1) application crashes; and (2) UIs that block on I/O. If we are really serious about making GNOME a viable Desktop Environment, I would like to see these as the next two GNOME goals.
That is all.
P.S. Thanks for your great work Federico :-)