The market have very rapidly developed during the last year or two where 2, 3, 4, 5 MP cameras are available to very affordable prices. Running 64 of these cameras in contusion mode or in motion detection in 25 fps will not work. However, for a couple of years ago it was 640x480 that was affordable and with MD and 10 fps it worked with a high-end pc. A high end PC today is an i7 quad core 3,4 GHz processor with SSD and at least 8 GB of RAM. There you also have possibility for hardware acceleration like Quicksync. A user reported that NCS got faster, but it sent the CPU load rather high which I don´t think is problem.
Even though MP cameras are much more affordable today one must ask if it necessary to have them? MP cameras usually comes with a large viewing angle. If one use motion detection how will that affect noise levels, objects on distance, alternative motion detection algorithms, ..... Lets go back to 640x480. It was much easier in the good old days Just kidding, but seriously putting all high end stuff together will not work in the end.
Considering your hangups there are some discussions in a couple of other posts with the same problem and it is under investigation.