What's a good guide to learn how to make (and see) vectorized code? It's a mindshift and not one I find easy.
Also read about SIMD instructions like AVX2. They are often used under the hood when possible, but just knowing what they require can help "triggering" them, depending on which language you use. In C++ for example, the compiler really looks for opportunities to use those instructions. You can tell the compiler did it, by looking in the assembly code if any XMM or YMM registers are being used (these are the names of the SIMD registers).
Numpy's tutorial for broadcasting is also a good starting point.
You can look at various tutorials to see how it works. For example: https://jakevdp.github.io/PythonDataScienceHandbook/02.05-co...