In 1976 she performed the roles of Fricka and Erda in the centenary Jahrhundertring production at the Bayreuth Festival, directed by Patrice Chéreau.
Schwarz made her debut at the Bayreuth Festival in 1975 in the role of Floßhilde in Der Ring des Nibelungen and performed there until 1998.
In 1976 she appeared as Fricka and Erda in the centenary Jahrhundertring production directed by Patrice Chéreau, in the repertoire until 1980, recorded for television and published on DVD.
In Bayreuth, she appeared also as Brangäne in Tristan und Isolde from 1981 and Waltraute in Götterdämmerung from 1984, as well as Roßweiße and Second Norn in the Ring, and Blumenmädchen and Knappe in Parsifal.
In 1979 she appeared in three roles, Theatre Dresser, Schoolboy and Groom, in the Paris premiere of Alban Berg's Lulu in the version completed by Friedrich Cerha.