Depending on what you want to do, Python with numpy could be an option. In terms of longevity, I don't think Python is going to repeat the 2/3 shenanigans any

Depending on what you want to do, Python with numpy could be an option. In terms of longevity, I don't think Python is going to repeat the 2/3 shenanigans any time soon so with python 3 you should be ok, and in terms of speed, numpy is used in many HPC applications: if applied correctly and depending on use case, writing C/C++ code that performs on par with it will be quite hard.