Calibration of an RTSP stream camera

I am looking at purchaseing MATLAB but have a few questions:

I've seen a lot of information and videos on calibration of cameras but I've not seen the use of that calibration in real time. Once you calibrate the camera(s), can you use the cameras in real time? (I would assume so, but want to confirm)

If you can use the distortion correction in real time, what kind of overhead is used? (I'm trying to determine how much CPU might be used and what is leftover for motion detection and recording.)