I know it's been sunny and hot. Evidently you spent too much time outside.
Maybe that's why you "applaud in the Name of God."
The ONLY time one could or should applaud in a Church is after the Consecration--the biggest miracle. Since we don't applaud then, what OTHER event comes close enough to that for applause?
Applauding the choir, however, is a travesty.
As a choir member, I detest applause with a passion. But I understand that people are ignorant of proper decorum (unless they've taught themselves or have been instructed from "on high"), so I live with it. Grudgingly. And how does an ill-catechized choir know that the applause is meant for God and not for them?
While I acknowledge and appreciate the fact that those that clap after Mass aren't the early exiters, applause is still cheap and lazily convenient for the applauders whenever it happens.
If you truly want to show your appreciation, take the time to see the choir after Mass - they're genuinely starved for a kind word instead of cheap handclaps. And say - and mean - something like "You helped me pray" instead of focusing on the presentation alone. (BTW, it's not a performance, it's a presentation to the Lord God. Or at least it ought to be.)
As for catechizing the choir about their ministry, "Non nobis Domine, sed nomini tuo da gloriam." would be a good, pithy start. (Translated by ICEL as: "It ain't all about us, folks.")