Graal won't make apps run faster. The responsiveness of most Java desktop apps isn't CPU constrained, like on the web, slow reactions come from elsewhere. On the web it's mostly the heavy reliance on the server to do basic tasks meaning there's roundtripping. On desktop apps it's mostly like on mobile - if you hit disk or do other slow operations from the GUI thread then you can get "jank".
Android here took a good approach actually, since developer education and lint checks apparently weren't enough, eventually Google changed the OS to kill an application that does such requests on the main thread.
I tend to think rigorous constraints are important to achieve software quality because when something stupid is possible someone's going to do it ("what's the problem? it works").
Kind of surprising then that not a single major 3D, music, office, or photography production software is opting to use web technologies for the GUI on the desktop.
On the web it’s mostly putting JavaScript between input and reaction/output, leading to input lag, and devs paying no attention to how much memory all those convenient JS data structures will eat and how slow it is to do stuff to them over and over. A few ms here, a few there, a ton of objects and lots of string concatenation, and boom, you’re using 1.5GB and your app feels slow as hell.
