In 2005, I was at a talk by Alan Kay. His ‘big reveal’ in the middle was that his talk was delivered entirely from Squeak.
This was after he had shown a full-screen video. The entire video decoder was written in Smalltalk and run in a bytecode interpreter, not even a JIT.
For most modern apps there is a very small set of things that are so performance critical that they need to be written and optimised in a low-level language. For everything else, you can and should use an environment that favours ease of use and extensibility over performance because the extra overhead will not show up to users at all.
I still don’t know how Electron apps manage to be slow. V8 runs JavaScript at least an order of magnitude faster than Squeak ran Smalltalk and my laptop is at least an order of magnitude faster than the one Kay used in his talk. None of the slowness is due to using a high-level language, it!s due to building a huge pile of the wrong abstractions on top.