Thanks for the screencast.
I was able to pinpoint a couple possible "pinch points" that may be causing the behavior you're reporting. One is that the snap is enabled in the sketch palette. This option will cause you to automatically snap to the nearest grid point whilel sketch and could cause the display to look a bit more "jumpy."
Another option to be concerned with is the 3D sketch option. This option will allow you to snap to 3D geometry. For a complex model, there could be a lot of geometry located underneath your cursor at any given point. Disabling this option may reduce total compute during sketch commands.
Another thing I noticed is that you are using a 3D space mouse. In some previous cases, this has been known to increase the graphics requirements. I would be curious if the same lag exists with the spacemouse disabled. It could be a good diagnostic procedure to run.
One more tip for complicated sketches with a lot of profiles is to disable the Show Profiles option. I've seen this help with sketch performance as well.
I hope these help.
Thanks,
Nathan Chandler
Principal Specialist