Important thread, certainly alerted me to watch out on my upcoming trip to FRA. Having said that, the complaint-to-advice ratio in here seems to be slightly suboptimal.

Is FRA complex? Probably, but so are FFPs, and this site is all about taking advantage of complex FFPs when most others wouldn't. So do the same when navigating FRA! FRA has not been my home airport for some years now, so not all information/terminology may be current, but I hope some of this will be helpful.

To begin with, use the FRA app before you even start your journey to the airport. The app provides waiting time information, and you can plan which checkpoint(s) to use based on this information. It would be nice if someone more current on FRA could comment on the accuracy of waiting time information.

The most obvious strategies to optimize checkpoint waiting times involve T1 only, starting with using Concourse B west vs. east (I believe west is right, east left if facing security). If the app states a difference in waiting times between these two, you know which one to use (I suppose even though waiting times are for regular queues, they are also indicative of priority queues on a relative basis). If B is longer than A, go to A and then make your way back to B once airside. As someone upthread pointed out, there are ways to play with security in Z (upper vs lower level; you may need status for this). Quite a few security checkpoints in T1, and you can navigate your way to any other T1 section airside once you've cleared any security checkpoint.

If waiting times are predicted to be very long at all T1 security checkpoints, using T2/the skyline may be an option (don't know if this still works). Years ago, you could get to T2 via skyline (landside), go through passport control into non-Schengen, take the skyline back to T1 (all the way to A IIRC), get out and go through security right upon leaving the skyline, usually with no queues, and then back through passport control to get into A Schengen. This, of course, also took some time, but would normally be much faster than the extreme waiting times experienced by some on here - and in any case, if I have the choice between being stuck in a queue for one hour and doing the skyline thing, I'd rather do the latter even if it takes the same amount of time.