Showing off refers to the person who's doing it; performing refers to the effect on the audience. No real conflict.

I agree to the extent that in cases where the is an audience gathered to be entertained - there is little or no conflict. The performer on stage can show off their talents and their ego and the audience will be entertained or horrified and the audience (especially a paying one) will be the judge of whether what they have seen is showing off or (a good) performance. And whether they would do it again.

The question is more in informal settings where there is not a defined audience or where some form of audience has gatherered to some extent but not for the purpose of watching any particular performer.....