Another scenario where it lags on higher resolution screens:
When moving midi notes during playback there is a huge lag. I uploaded 2 videos where you can see the issue. On the smaller resolution monitor everything is as smooth as it can be.
High resolution monitor:
https://www.youtube.com/watch?v=9_PNTv2Vx_o
Lower resolution monitor:
https://www.youtube.com/watch?v=hrTnz6VtkJk