I'm an avid Elite Dangerous player. My suggestion for the upcoming M2 demos would be to run some of the ED Tutorials ("Training Missions"). Imo, this would be the best way to quickly demo ED.
I would recommend the "Basic Flight", "Docking and Travel", "SRV", and "Mining" missions (in that order). Keep in mind that playing ED requires knowing a lot of commands and most players have custom HOTAS setups, so what you want to do is show a variety of scenes, without much need of ship flying. These tutorials will quickly give a feel for how ED will perform, without needing to fly around very much.
Basic Flight: shows an extensive ice asteroid field with lots of objects
Docking and Travel: shows the interior of a station (which is a demanding low-framerate area)
SRV: shows a planet surface (another demanding low-framerate area)
Mining: shows a sparse asteroid field with a large nearby sun