I ask you about the settings you use in OBS.
Settings may differ based on hardware specifications but this is what I use and tested on my end. You should check out all available settings yourself and judge by yourself. I personally use Action!, since it's pretty much the best recorder out there right now but OBS will work just fine as well. You cannot use "game capture" for NWjs or Browsers in general.
Output:
Video:
Scene (window capture):