Stripping out Maps/Lists with boxed keys and values is the first easy thing to do when perf tuning a piece of code. It's so frequently impactful that it's worth

Stripping out Maps/Lists with boxed keys and values is the first easy thing to do when perf tuning a piece of code. It's so frequently impactful that it's worth doing immediately without any measurement. You just swap them out with fastutils or trove and call it a day.