Python is the way to go. Since all opengl programming is uploading data to the video card RAM, then using opengl to operate on it, the speed limitations in python are moot. Also it makes the hard things in C++ easy ie opening files, images, sounds etc.
As for the person above implementing octrees, there is nothing stopping you from using numpy, which is written in C, from implementing it. (also make sure you are using linear memory like a binary tree, and not pointers to objects in a link like structure)
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