C/D effectively share the same security checkpoint. On one side, using the walkway closer to the D tram, is non-PreCheck. The other side closer to the C tram has Precheck, CLEAR, airline elite priority/first class, known crewmember line, etc. Regardless of which side you go through, the door that separates the C and D trams is always open.

I don't have enough experience with T3 to be able to compare it with T1, but you shouldn't have trouble with the C/D checkpoint. (I'm sure you already know, but even with PreCheck, it's possible to be randomly selected at which point they will ask you go through the nude-o-scope and you can opt-out to receive a patdown instead)