While it's possible to write a Swing application that runs fast (starting fast is a different matter), it takes quite a bit of effort to do so, because the basi

While it's possible to write a Swing application that runs fast (starting fast is a different matter), it takes quite a bit of effort to do so, because the basic tools that it provides lead you towards slow applications and a lot of boilerplace. Any shop that ever did a bunch of Swing and cared about quality ended up writing their own layer on top of Swing that made those features easier to use, but they still require quite a bit of discipline. UIs is the kind of place where the whole reactive model actually works well. Create events, subscribe to events, and make each event handler run asynchronously. Use the dispatch thread for events that actually modify frontend-facing, elements, and everything else on background pools. So the broadly available toolset could only be used well by programmers that are better than the typical guy that was asked to write the UI, and we never got better tools.