There's a bit of a dispute ongoing in Irish trad circles about the "speed thing." At its core, the traditionalists point out that the music originated primarily as dance music and should be played at a "danceable" pace. The "other side" tends toward the view that a faster pace allows for demonstrations of virtuosity. You'll find a wide distribution of ages and skill levels in both camps. Like so many other great debates, threr really doesn't have to be an "either or" solution. Both are likely here to stay, so pick the pace appropriate to the audience.