Games and Applications aren't that far apart, most titles will be developed on existing engines that are predisposed to certain genres/constraints and will need

Games and Applications aren't that far apart, most titles will be developed on existing engines that are predisposed to certain genres/constraints and will need to work within that the same way that UI frameworks limit what possible things an application can do(which is quite a lot). I've spent a decent amount of time in both spaces in my career, it is totally possible to build performant, fluid applications but it requires a degree of care and investment. Usually "good enough" suffices and that's where things land but there are also developers who prioritize that and short of very restrictive environments you can build responsive applications. Besides, at the end of the day all UI is doing is rendering, with a direct path to the GPU just like games do :).