180 fps in opengl for 60 fps in OBS

[ogmkp]

I would like to know if it is normal that the OpenGL managed in OBS displays 3x the fps than the demand required in OBS.
Exemple, for 60 fps in OBS, OpenGL handles 180 fps (linux and nvidia in my case).
How to explain this ratio ? It's normal?

I'd like to know if it's normal to have, for example with a simple source in a scene, a render time of 1.7 ms at 60 fps but 0.4 ms at 120 fps?

Thanks.
@Fenrir

 

[ogmkp]

After searching, I see that obs is coded as a double buffer without egl swapping, a backbuffer to draw a frontbuffer to display the frame.
So it's not vsynced, which speeds up graphics composition and means it don't have to wait for the screen.
So I have 120 fps in studio mode, which adds 60 fps when a source property is open, but why do I only have 60 fps in non-studio mode?
What would be the effect of triple buffering and would it lengthen rendering times?

As a poweruser, I'm trying to understand.