> The problem is that writing genuinely performant Java code requires that you drop most if not all of the niceties of writing Java

Such as? The only area where you have to "drop" features is high-frequency trading, where they often want to reach a steady-state for the trading interval with absolutely no allocations. But for HFT you would have to do serious tradeoffs for every language.

In my experience, vanilla java is more than fine for almost every application - you might just benchmark your code and maybe add some int arrays over an Integer list, but Java's GC is an absolute beast, you don't have to baby it at all.