`--gc:arc|orc` are on the way to become the default choice for memory management. ORC is just ARC with a cycle collector (so you don't need it when you don't have cycles)
Also for leaks you should compile your program like `--gc:arc -d:useMalloc` and then run it with valgrind like `valgrind --leak-check=full ./program`. This might not be needed anymore with [https://github.com/nim-lang/Nim/pull/14467](https://github.com/nim-lang/Nim/pull/14467) though
