One of Julia's main selling points has been speed. They said there was no reason a dynamic language had to be slow, but now we see that as soon as they start adding basic features, such as support for missing values, it's beginning to take a toll on performance. I wonder if Julia 1.0 will be any faster than R or Python.
> ...now we see that as soon as they start adding basic features, such as support for missing values, it's beginning to take a toll on performance.
Of course there is a price to pay for adding dynamic features, but only when you use them. This has been the case for Julia as long as I can remember (for example, fields of type `Any`). As far as I can see, isn't the whole point of Julia that you can go towards the dynamic end of the spectrum if you need to, while still being able to generate blazingly fast code by adhering to type constraints wherever it is necessary? All this within the same language, rather than with R and Python where you need to write extensions in a lower level language and deal with a C API.
I'd encourage you to read the post again, since it's primarily focused on describing design patterns that allow one to support missing values without taking a performance hit.