General:
* A company of performers
* A troupe of performers
* A cast of performers (especially for actors)
Specific:
* A choir of singers
* An orchestra of musicians
* A band of musicians
* A ballet of dancers
* A crew of acrobats
* A team of comedians
You could also use a more descriptive phrase, like "a gathering of talented performers" or "a constellation of stars."
Ultimately, the best collective noun depends on the context and the specific type of performance you are describing.