Video keeps pausing with virtually low resource use when recording Windows capture

[Coimbraguy]

Hi all, I am new here. I have read already many instructions.
I am trying to record a video session for which I payed for but I need to watch it offline, and it does not come with download option.
I reduced the image frame to the center of the black background. I am watching the video in Firefox.
This is the Log File: https://obsproject.com/logs/AXYlxdm7ziJeWHQU

So I start the A/V recording in indistinguishable mode and low CPU usage preset. With this settings, I get a CPU usage of ~20-33%. If I use the other setting (Software x264), the CPU usage is around 6%. Either case, the video starts to stop for 2-3 seconds after 25-30 seconds of recording, and it keeps happening in every 10 seconds or so. There is no problem with the sound. I ran OBS as an Admin, I tried different settings. I first disabled Nvidia driver, then I restarted OBS, and I got rid of the encoding error. Yet, I still have this problem of pausing video during recording.

Any help will be appreciated.
P.s. my OS is a bit outdated but its update is not an option, because I have a couple of programs I need for work which don't work after windows update (and I don't think this should be the problem here).

 

[Coimbraguy]

I tried then the 3rd setting: Hardware encoding (H.264). This worked beautifully without stopping. And 3 minutes in the recording, the screen went black and displayed: Error encoding. So I quit OBS, I disabled Nvidia, launched OBS, re-enabled Nvidia, and now the video keeps pausing for seconds immediately from the beginning. So far, it just got from bad to worse.

 

[Coimbraguy]

Now I think I understand the problem. The proper OBS software during recording affects the video playback in Firefox. That is, the stream starts to pause after a few seconds when I do the recording. I wonder why because the CPU use is very low.