Are we talking Shengen or Non-Shengen?
For Shengen I dont think I have seen more than a 10 minute wait in the past years, though often (almost always) an annoying ~10 economy pax being led to the SP line.
For non Shengen upstairs its a different story. Monday morning around 8.30AM; the holding pen totally full until (and slightly beyond) the boarding pass scanners. Still was able to clear the line in about 30 minutes though.