For a digital tuner, NextPVR is, simply stated, "copying" the broadcast stream. For example, to create a recording NextPVR "copies" (part of) the broadcast stream from the tuner to the hard drive to create the recording file. This process places very little load on the processor. I have had NextPVR record twenty channels simultaneously without affecting the playback of a recording on the same machine.
Originally Posted by eastavin
It is not likely that there is a significant generic difference between PCIe and USB tuners ... any difference is likely to be more or less undetectable.
You can test all this with your current tuners by recording as many simultaneous shows as your current tuners allow and using Task Manager to monitor CPU usage.
AMD A75, 4 Gig, 1000 Gig, Nvidia N210
1 x Hauppauge WinTV QuadHD DVB-T2
1 x TBS 6281 dual DVB-T2
2 x Hauppauge Nova-t PCI