Annoyingly high input and redisplay latency (probably not fixable, just an inherent property of the very chatty X protocol).

Unless there's a program specific to your environment that is causing this, I would say that this is partially fixable. There's some kind of bug/weird implementation detail in the macOS vsync driver that causes massive lag in XQuartz.app and macports' X11.app.

https://www.youtube.com/watch?v=IaPh4tc0_B0

If you use XQuartz regularly, I would highly recommend you install Quartz Debug.app so you can disable vsync before you hop into X.

https://download.developer.apple.com/Developer_Tools/Additio...