I'm not sure. CLT feels like an immigration mess around 2-3pm. Unless you have GE, APC doesn't speed up the process since they make everyone queue in the same freaking line after clearing the machines. Honestly, even LAX or DFW is faster as you'll go to a different queue, once you've done APC. In CLT everyone is using the same line in the end, APC or not. Doesn't make any sense at all.
I've just got into CLT the other day with a companion that had not yet received his GE. From the moment we got into the immigration area it took us 60 minutes to clear it. Inefficiency at its best.