Comment by kragen

Typically straightforward Numpy gets me from 40× slower than straightforward C to 5× slower. Tricky Numpy (output arguments, conversions to lower precision, weird SciPy functions) gets me another factor of 2. C SIMD (intrinsics or GCC’s portable vector types) gets me a factor of 4 faster than straightforward C. Presumably CUDA would buy me another factor of 100 but I haven't tried it and I haven't tried Numba either.