I took python more as a motivating example than an absolute. As far as I can tell the article suggests developer speed over application performance. Then FFI

I took python more as a motivating example than an absolute. As far as I can tell the article suggests developer speed over application performance. Then FFI to a "fast" language to overcome your performance problems. That way you only pay the overhead of a high performance, slow to develop language where it actually matters. Which is usually much less than the whole program, so not paying for performance where it isn't needed is a big win.