I am not sure that the runtime efficiency of the compiler binary is that important. People like fast compile times, but that is more to do with language design than the choice of language for the compiler.
You could write a compiler for Pascal in Python or another very slow language and it would be faster than a Rust or C++ compiler written in Rust or C++. That is because those languages have designs that make compilation algorithmically slow, while Pascal was designed to be fast to compile.
You could write a compiler for Pascal in Python or another very slow language and it would be faster than a Rust or C++ compiler written in Rust or C++. That is because those languages have designs that make compilation algorithmically slow, while Pascal was designed to be fast to compile.