One last comment for other beginners like me:
While it was already said that type parameters in functions don’t affect the speed, if you have a nested custom function within a custom function, and you do not want to set that function as input in the outer function, you can speed up the performance drastically by declaring the return type of your inner functions like myfun(...)::Float64.
I think this is called setting function barries in the performance tips, and was answered in another of my questions here: Large memory allocation in function within function - #4 by mrVeng