To me, it depends on the church. I have attended churches where applause is the norm, and I clapped. I have attended other churches where nobody ever clapped, and I remained silent. You need to respect the beliefs of the church you are attending, and the order they have established. I don't know of any scripture that would say you were right or wrong to clap for something said in a message, but it isn't really any differen't than saying A-men in agreement. I am not as sure about clapping for a performance, but there is nothing in scripture that says it is wrong.