"Whenever applause breaks out in the liturgy, because of some human achievement, it is a sure sign that the essence of the liturgy has totally disappeared and been replaced by a kind of religious entertainment." Even though Cardinal Joseph Ratzinger was talking about liturgical dance when he made this statement in Spirit of the Liturgy, it applies to applause for all human achievement at Mass.
People at my church routinely applaud for the choir at the end of Mass, after the recessional hymn. True, Mass has ended, but people are still standing in the presence of Jesus, who they have just received in Holy Communion, and Who just reenacted His Sacrifice on Calvary. Shouldn't this time be spent in interior recollection and prayer for an increase in grace from the heavenly food that is present within us, nourishing our soul? Instead, the focus is on the choir, and the need to show appreciation for their efforts. We don't clap and applaud for Jesus as He sacrifices Himself to His Father for our spiritual benefit at Mass, and neither should we applaud each other.
As Pope St Pius X said,"It is not fitting for the servant to be applauded in his master's house."