Can you add more details about your setup, as detailed in https://retropie.org.uk/forum/topic/3/read-this-first ?

Does this happen to all games or just a few games ? Which version did you have installed before the update (or when was the previous time you updaed) ?

@buzz
You have a good point.

I had a very similar problem to this thread. I replaced my Pi 3 retropie with a Pi 4 and retropie was behaving in a jittery fashion with Emulation Station and the games weren't smooth. I also have a 4K Samsung Smart TV as did the original poster. Although I wasn't using Amiberry, I was using mame, daphne, and jzintv and I figured the same solution that @gordonfreemanjr used would work for me. So I added the five lines to my /boot/config.txt file that he listed in his "IT WORKS" post but lo-and-behold it did not work for me. tvservice -s was still showing a 4K connection when I expected 1080p.

My solution was simple with a twist. Starting from the stock config.txt, I uncommented and modified the following:

hdmi_group:0=1 hdmi_mode:0=16

It was necessary for me to add the :0 to get it to work. Now there are no jitters, the motion is smooth, and tvservice -s reports a 1080p connection.

Classic remark in case it's the issue: can you try disabling vibration in the Retroarch core options menu and seeing if it improves it?

@xl97 second controller should just work. does it work for 2 player in other lr- emulators (like SNES, etc)?