Thank you for comprehensive reply.
My CPU load during monitoring (no recording, but motion detection on) stays at 15-17%. During actual recording (which involves real-time recoding as I understand) increases to 35% as measured by Process Explorer for total system usage, where Netcam is practically the only CPU consuming program (this PC has no other tasks).
Now my recording settings are:
Quality: CRF 30
There is now 1 IP camera (Wifi) with 720p stream over RTSP (Escam Q6 button camera). Most of the time the recording is quite smooth (10fps) but still ocasionaly there is a freeze frame for 1 or 2 seconds, typically at the beginning of each new video file. Earlier with higher encoding Preset, like Fast (or higher), it could barely make 1 fps on each recording.
The CPU is Intel Atom Z3735F. I am well aware it is no performance demon, that's why I feel that the camera's hardware potential of delivering the already encoded H264 stream is wasted. But the Windows system runs pretty well on it.
I will take a look at the CMS software provided by Escam, because I think it will simply retrieve and save the original H264 stream from the camera.
By the way, now when I look at it, spending few hundreds bucks for a PC based NVR (to make it a Core i5 or so) seems unreasonable when compared to getting a hardware based NVR for 30 USD with embeded Linux and software (adding a 500GB HDD for another 50 USD, which still puts me under $100) - it can do 8 channel 720p recording.
Unless I am missing something out?