I've never used the A FCL before. If I'm starting in FRA I use the FCT & my connections have always been INTL-INTL so use FCL B (a ridiculous walk from far Z gates)

In a few days I'm coming into Z & continuing to CDG so I'll finally have a need for the A FCL. Is it a quick walk from Z (I know Z is directly above it but do I need to walk all over the place to go thru immigration & security? I've seen the A security line around 05:30 before and it can be a zoo even at such an early hour. Do I go to the same security line for A as those beginning travel in FRA or is there a short cut (do I even have to go thru security from Z to A??