About a half-second lag during capture

[7z7]

I checked on the same PC with Windows 8.1, 10 (fresh installation) and 11 (fresh installation) with MoBo Gigabyte H87-HD3, Gigabyte_GV-N75TD5-2GI [GeForce GTX 750 Ti] and 16 GB RAM.
When capturing a screen or window, I observe minimal lag (every second or so) when there is object movement in the video.
The original video plays back smoothly.
Is this a feature of OBS?
If not, where to look for optimization?

 

[7z7]

I use two real monitors. video is displayed on the second monitor, and OBS is open on the first monitor. Both monitors have a resolution of 1280x1024.
Capture is set to a bitrate of 4000 Kbps.

 

[7z7]

I don't even have to capture the video, because in the preview window, the video also freezes for fractions of a second. It looks as if some buffering is going on. It doesn't bother you if you don't pay attention to such subtle interruptions, but now that I see it, I can't use OBS.

I checked on an HP 470 G7 i7-10510U with 32 GB RAM and the effect is identical.