So you are in the very niche use case where:

- you need a GUI

- you need perf beyond what Python is capable and you identified it clearly in advance

- you can't use numpy / multiprocessing / cython, pypy or they won't give you the perf you need

- you can't find a main hotpath you can optimize with a 5 lines c or rust extension and write 99.99% of your app in python. Or you don't want to bother.

If you ever find yourself in this very use case, then yes, use Java.

But I never found myself in this very precise use case.