Strange screen behaviour with tearing

[Luca Osvaldo Mastromatteo]

It's a known issue the amount of screen tearing when using the Optimus NVIDIA card, and with PRIME sync this is partially fixed, but the games are unplayable due to the input lag.
But I'm figuring out another issue that I'm not sure about what the cause can be.

I'm getting solid fps in games, but they feel choppy and different from Windows even with the same fps, tested in a lot of games, I don't know if that has something to do with the screen tearing but they look like false fps drops or a screen refresh rate issue, I'm 100% sure that they are not fps drops, the fps are stable, so that's why I think it could be extreme screen tearing or refresh rate, this is very annoying when you play games.

Screen tearing is obviously occurring also in Windows, but in there it doesn't feel choppy as when playing on Linux.

Same games on my non-prime desktop, with the same NVIDIA driver feel a lot different.

NVIDIA driver 410 (from graphics-drivers repo)
Kubuntu 18.10 with compositing disabled
Tested games: Steam half life 2, Lutris DXVK Overwatch and Heroes of the storm
NVIDIA GTX 960m on Dell XPS 15 9550 i5 version

[Luca Osvaldo Mastromatteo (lukycrociato)]

Forgot to say that playing on the external monitor seem different even with the same tearing.