It is virtual in the sense that it does not realize the entire dataset in the JS side of the WebAssembly bridge - this is a performance optimization but entirely in-memory. While you can run the engine in node.js and use it to efficiently stream updates to a symmetric engine in the browser, we do not currently implement server-virtualized views.

Though, we have quite alot of experience doing this in the past - and the design of Perspective is very much a reaction to what we learned, at lesat in regards to the typical financial dataset which is much smaller than 1TB.