[jstepien]

I couldn't sacrifice performance (lots of number crunching was involved with costs tight), so, I couldn't pick Python.

PyPy, Cython or Shed Skin might have been answers to those number crunching problems. I'd love to learn whether they would be sufficient for OP's performance requirements. Some benchmarks look promising, for instance this one published in late 2010: http://geetduggal.wordpress.com/2010/11/25/speed-up-your-pyt...