Input Lag: 26.4 ms
With Interpolation: 110.7 ms
Outside Game Mode: 119 ms

The very low input lag is among the best you can find when you set the TV to game mode. In PC mode, the input lag is still good, at 34.9 ms.

The stuttering you see should be viewable on other sets. There's only one clue in your post. That audio mixer. I've seen folk that call themselves video editors burn up over rigs like that. They get upset so you give them time to simmer till they are ready to try again. The rig if it's like others is the cause. Not the set.