ICC is not slow games.
Standard time control mostly means something between 15 0 and 20 20. Which is not slow. And the same 45 45 league and STTourney's 60 0 count into that standard rating as well which doesn't make the picture much clearer.
Fewer quality players play standard. 15-minute got a little better over the past few months with a few more titleds, but I think all in all it's more boring compared to 5-minute and blitz.
Blitz is more defined since it has a lower and upper time bound as well, but blitz is different from both CC and 'slow' play. Especially if you have a good mouse.