Mac external 4k monitor - choppy

Hi!

I have a Macbook Pro 16'' (2019). I have a 4K external monitor that I am using with a display port/usb c. The video, when played on 4K on this monitor, is very choppy (it is not on the Mac display, though). I tried to play with the display settings but am unsure how to correctly adjust it. I tried to scale it (unsure if it affects performance) and I am unable to see settings for the refresh rate (but I do see it for the Mac screen).

Any tips on how to remedy the situation? Could it be the cable?

Thanks!

Monitor details: Samsung U28E590D 28-Inch , 3840x2160, 133.3kHz, 60Hz