How big can the graph get before taking a noticeable performance hit? A better example should be shown if advertising "Big ... Data"
1 Reduce the number of nodes and edges, thus increasing capacity
2 Combine nodes that should be seen together (e.g. alternative spellings and typos), to better deal with the variation-aspect of big data
I see your point, but the goal here was to illustrate the functionality.
In general, using right click on web applications is a terrible idea, since the standard function in browsers is to show a context menu for the clicked element. IMHO a lightweight selection mode or quasimode would work better.