[DNF2]

I have no particular opinion on the teaching materials, I just use the manual and the discussion fora, so I don't know. But if a third party offers teaching materials, it's not so strange if it resides on their third party website.

As for performance, I'm not really talking about 'optimization'. Your implementation may simply have used some pattern that should be avoided, such as global variables, type instabilities, abstract types in structs, or some inappropriate data structures. If it's a microbencmhark, then there are some things to keep in mind.

These are not really optimizations, but basic performance principles. I cannot know that you are unaware of them, but your statement that 'there's not a lot to optimize' make me suspect that this could be the case. The unusual thing about Julia is that it's both dynamic and compiled, so that code that would simply not compile in static languages instead ends up slow.