From above - 'You can't play Irish too fast'.
Oh yes you can! - and that is the trouble with MOST Irish sessions that I have ever been to - listen to some of the old Irish musicians and even some of the younger ones like Mary MacNamara and they take it at a lovely steady pace - allowing time for the tune to develop and space to add in little flourishes and decorations.

I have been running a session for over ten years - pretty well all English tunes with the ocassional tune from elsewhere, and a few songs. A lot of the regular musicians are well known nationally and well regarded for their knowledge and expertise. I run it as a 'tunearound' usually - i.e I start with a tune, then go round the room asking people to lead us in something....and we do like to wait until something has been played through once before we all join in - it might well be a different version to what we expect!
Dave