The largest orchestra group that ever performed was in Commerzbank - Arena, a soccer field in Frankfurt, Germany. The orchestra had over 7500 musicians and they are performed at the same time. They performed excerpts from symphonies by Beethoven and Dvorak, they performed a 1976 pop song by John Miles titled 'music (was my first love)' and they performed melody from starlight express.
They performed for over 45 minutes. The director, wolf kerschek was put on a 500 square metre video screen so every one could see him.
Before the time this orchestra was performed, the record was reached in Brisbane, Australia in 2013 when 7224 musicians played together.