https://issues.dlang.org/show_bug.cgi?id=13410
--- Comment #39 from Steven Schveighoffer <schvei...@yahoo.com> --- Bearophile, With the tree-based solution, when the front element is removed, the "next" element is 1 hop away. But with hash, it can be far away in the table. So you likely are better off using a tree-based map, something like RedBlackTree if you want to come close to C++ performance. There is also the issue that C++ uses a template-based map, so it can optimize the code, inline comparisons, etc. The AA-based solution cannot do this. --