
both are correct.
the latter is more grammatically correct because it addresses the orchestra as the one entity by using the s in the end of performs.
the first is not 100% accurate but this approach is seen more and more frequently, especially in British English, when a single group of people (an orchestra, a company or similar) is addressed as multiple people - therefore the s is dropped, and the orchestra can be addressed as they rather than it in later sentences.
hope this helps ☺