Salonen brought his particular creative energy as conductor-composer to his direction and participation in the Festival of Contemporary Music and to his conducting of the Boston Symphony and of the Tanglewood Music Center Orchestra. That crowning performance was of Bartók’s Concerto for Orchestra, a cornerstone of 20th-century repertory and a superb orchestral showpiece that was commissioned by the Koussevitzky Music Foundation. (Subsequent important orchestral concerti have been produced by Witold Lutosławski, Roberto Gerhard, Henri Dutilleux, and Elliott Carter.) The genre of orchestra concerto grows out of the baroque concerto grosso, in which some subgroup of the orchestra acts as soloist against the backdrop of the entire ensemble. Salonen set a dizzying tempo, leading one to imagine that, if kept up, the players’ arms could fall off (they didn’t).