Originally Posted by stlBased

Agreed that when it's backed up on the 'normal' lines to the left, the First Class / Employees line is a big lifesaver. It's helped me have more breathing room to catch a flight more than once, especially on an early morning departure Mon or Tues.
However - the bottom line is that A concourse security in STL is a total crapshoot. The biggest determinant to how long it takes is what time of day and whether they have more than 2 lanes open...and it's not a linear relationship - there are times when it should be slow and they've backed down the staffing so that the lines end up being long - at other times you might expect it to be busy (morning bank of flights) and they've got 4 lanes open so it's pretty efficient.
You may also have the misfortune of being in the First Class / employee line as a gaggle of flight crew come through (always seem to come in bunches) - I've witnessed, no joke, 4 separate crews come through in rapid succession. 15 people jumped to the head of the line (I really don't have any problem with this, just really slowed up that FC line that day) and made FC security much slower than regular.
The other thing is that in my experience, it's not a true SkyPriority or Elite line. It's labeled (not too conspicuously) as First Class / Employees only. When I'm upgraded to F I use it. When I'm not, I generally hit the main line.