Try another GC, I know that there are (were) some leaks on small memory allocations that were not returned to the OS.
For full debugging, compile with `--debugger:native -d:useMalloc` and pass the program through Valgrind. That will replace all the GC calls by system malloc and Valgrind will be able to do its magic. You might want to compile in release mode but with `--stacktraces:on` for speed (or maybe stacktraces don't need to be on with debugger native, not sure)
