There was practically no applause after Mozart's String Quartet in G, K. 387, yesterday afternoon at the World Bank. Not that the audience was unwilling, but there was no time.

The Manchester String Quartet silenced the applause almost immediately. It took a quick bow, sat down again and launched into the Clarinet Quintet with Loren Kitt, who had suddenly materialized on the stage. This was a lunch-hour concert, and the players had to assume that the audience was full of clock-watchers anxiously observing the approach of 2 p.m.

They did not quite make it. Some performers (James Galway, for example) have been known to play as though they were hurrying to catch a plane. Not the Manchester Quartet, and certainly not Loren Kitt; the music dictates its own pace, and the musicians are its servants. The concert went on about seven minutes past the hour, and every second of it was delicious.

Beginning the second year of what may become an annual Mozart's Birthday Festival, the World Bank is, if anything, a victim of its own success. All 300 seats were filled in its auditorium at 600 19th St. NW, and an overflow audience of about 100 stood or sat along the walls. A few left after the quartet and more during the quintet, but at the end there were still many more patrons than seats. Perhaps when it begins its third year, the festival should arrange for two performances of each program.

The World Bank seems to be in an ideal location for a festival of free lunch-hour concerts. In a neighborhood frequented by the staffs of the White House and executive departments, the State Department and George Washington University, not to mention the World Bank's own polyglot personnel, the potential audience probably has as high a daytime concentration of well-educated workers as any in the United States. These demographics were represented in yesterday's audience -- informed, attentive and apparently eager to skip lunch for a quick diet of Mozart's chamber music. If the same audience returns for the remaining four days of the festival, which will sample Mozart's music for voice, violin, piano, piano trio and wind instruments, there should be some thin but happy people around 19th Street by Friday afternoon.

Yesterday's program was superb -- a vintage quartet from the great set of six that Mozart dedicated to Haydn and a quintet that is one of chamber music's prime glories. It received a performance fully worthy of the music, vigorously expressive, delicately phrased and balanced. The remainder of the week will feature some of Washington's finest musicians in some of the world's finest music. And the price is right, even if it includes returning from lunch a few minutes late. Those who prefer to sit through the music rather than stand are advised to arrive well before the 1 p.m. starting time.