My understanding is the compiler was insanely efficient and parts of it coded in assembly if I'm not mistaken.
one thing for sure is that it felt near instant if not real time building small projects, to the point that 14yo me was completely unaware of meaning of Compile until years later.
Yep, designed to be single pass, recursive descent friendly
Because of this feature, the language could also support mutually recursive functions, which some other languages might not have been able to (not sure).