I might be able to help you on this as I got very bad juddering/stuttering when I had a new TV this year but mine was Samsung.
My issue only related to the raspberry pi 3 all other devices connected to my tv for example xbox, my Bt TV box and all the streaming apps on the TV didn't stutter at all but by changing a setting on the TV solved the issue.
I disable a feature on my tv called motion plus, on your LG TV this setting is called trumotion.
I first disabled this just for the pi as modern tvs allow you to change settings per hdmi input but after doing a little research on these settings built into these modern tvs it appeared a lot of people do not like this feature as it causes a soap opera effect like picture.
After playing around with these picture setting myself I decided to turn this motion plus/trumotion feature off completely as it gives a more normal look to the video content being played.
I don't know why this only caused stuttering on the raspberry pi hdmi input of my tv but either way disabling it solved it for me and I was more than happy to disable completely after comparing it on/off with other video content from other devices.
Games consoles are not effected as my tv auto puts the TV into game mode which disables all these TV features so called good features that pack tvs with nowadays.
Hope this helps