Any slow song can be slowed further.
"Ev'ry Time We Say Good-bye" by Cole Porter can be brought way down in tempo and volume and practically whispered into a mike provided you don't make it repititous.
(Have you ever heard Chet Baker sing? Find a recording. He made you want to fall into bed with him. His technique was so intimate that he practically put the mike in his mouth, but the sound was phenomenal. Every song is a seduction of sorts.)
The bridge can be lightened a little and sped up a tiny bit. The line "...but how strange the change from major to minor." has to be reflective.
Smiling-though-tears and sadder-but-wiser leads an audience where you want to take them better than just tears-and-sad.
Still, any song that begins with the devastating line, "Ev'ry time we say good bye I die a little." is made for the heartbroken and depressed among us.
As wonderful as Porter's music is, this song is about lyrics. Enunciate.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher