The Salzburg Festival in July and August is the Big One. So, what about the Whitsun Festival? As Cecilia Bartoli, who took over as artistic director in 2012 has said, “it’s just one weekend.” Such modesty becomes her—but, my, what a weekend she lays on year after year, surrounding herself with the starriest talents in programs exquisitely balanced between the surefire and the longest of long shots. Onstage, she’s the festival’s workhorse as well as its queen bee, invariably juggling assignments most colleagues would spread out over weeks. This year, she steps out as Pleasure in Handel’s cascading allegory Il Trionfo del Tempo e del Disinganno (The Triumph of Time and Disillusionment), as the vacillating Sesto in Mozart’s La Clemenza di Tito (The Clemency of Titus), and in some ways most delicious of all, as the offstage Shepherd Boy in Act Three of Puccini’s Tosca—the role of her first public appearance at age nine at the Rome Opera. Anja Harteros, Jonas Kaufmann, and Bryn Terfel do the heavy lifting as the diva, the revolutionary firebrand with the paintbrush, and the mustachio-twirling chief of the secret police. —M.G.