Violinist Leila Josefowicz performed a recital at the Kennedy Center Saturday that featured a jagged, percussive repertoire. (Chris Lee)

Leila Josefowicz, violinist extraordinaire, opened a semi-residency at the Kennedy Center with a recital Saturday at the Terrace Theater (she'll also appear with the National Symphony in January and April). Josefowicz has distinguished herself with a strong advocacy for contemporary music, commissioning and programming new works throughout her career. Saturday's recital raised some concerns about the effect this repertoire — much of it jagged, percussive or even brutal — is having on her once-pristine conventional technique, but Josefowicz remains a sovereign artist who invests these thorny modern works with the same committed fervor as Perlman playing Tchaikovsky, if not more so.

The commitment to recent repertoire is not just lip service; though she now probably has several programs' worth of music written especially for her, the recital consisted entirely of earlier 20th-century pieces and arrangements ("Calices" by Kaija Saariaho from 2009 was based on a concerto from 1994). The only work you'd have heard elsewhere was the Prokofiev Sonata in F minor, which Josefowicz devoured, from the gossamer, wind-swept scales that end the first and last movements to the almost frightening violence of the "Allegro brusco" movement. Her longtime partner, pianist John Novacek, matched her kinetic energy, though he might try to tame his feet a little; it seemed at times as if he was playing a drum set.

The other principal work was the Bernd Zimmermann Sonata (1950), hovering between tonality and expressionism. There were harmonic patterns and motifs that peeped through the dense chromatics; and Josefowicz, playing from memory, drew a standing ovation for her intense delivery. I'm sold — the piece is undeservedly neglected. The Saariaho was less appealing, its three movements relying too much on sound effects (from both instruments) rather than musical ideas. Interesting but arid.

In arrangements of lyrical pieces by Sibelius and Mahler and in Charlie Chaplin's "Smile," though, Josefowicz never relaxed. Her efforts over many years to master and deliver often-unviolinistic music appear to be taking a toll. I longed for a phrase that simply grew, one note to the next, like a singer; instead the lines hiccupped or gasped, the vibrato intermittent or delayed. Her left-hand action is more gnarly than you see in YouTube clips from 15 years ago, the fingers crawling around rather than maintaining a natural, curved position. And though she executed Saariaho's many glissandos with grim efficiency, she seemed indifferent to the most magical moment in the entire recital: the return in the Mahler "Adagietto," where the violin line glides down more than two octaves in a languid, yearning sigh.

I have admired this artist for decades, and still view her as the model musical citizen, doing her part to help the art form evolve and remain relevant. I hope, though, that she takes care of herself and tries to remain connected to simple beauty.