I have observed that speed is not the best interpretation for the feeling of the tune.
This is a redundant comment, I know, but so much of Irish music is based on dance,
either home set-dances or step-dancing that it should become obvious as it is in jazz music that speed for its own sake is silly.

I like to hear an irish tune without too much ornamentation (which obscures the tune) or
done too fast to keep the notes away from the ear.

Music is not a gymnastic feat. The BPM obsession comes from an instinct by those that possess a gene for finger-dexterity to let it run away with them. In jazz, BPM becomes less of an expressive agent even though the jazz musician is capable of playing fast if needed.
(Check Charlie Parker).

What makes Irish music Irish is not speed but lilt (as Capt. Birdseye says) and feel.
I've heard too many American groups not get it right because they are Johnny-come-latelys to the music. When a music is culture-based such as jazz, growing up in it
requires different tempos to express variety.

Interesting is that there is a slight swing to Irish music not unlike jazz. It almost
has a 12/8 feel to it. (Lilt).

What excites the audience for Irish music is not speed per se but a kind of passion
that is uniquely Irish and a sense of lyricism in which the Irish music excels. I think
that speed for its own sake would be laughed at in the Comhaltas seisiuns.
Someone who tried to do that would be stepped on as a beginner.

So, it's like Bluegrass which for a while prized pyro-technics. Then the music
outgrew the gymnastics. Same for Americans playing Irish.

Stringsinger