Rust encourages a kind of generic programming that can result in generating too much code.

The compilation model is vastly, vastly, vastly better than languages like C++ and C, though, and it does compile much faster than an equivalent C++ build (doesn't count if you download precompiled binaries of your c++ dependencies)

That's not a paradox, that's how it always works. Compiling to fast machine code requires more work and takes longer.

Is Python a fast language because it barely takes any time to compile the code? No obviously not.

There's no paradox here. You can use any benchmark you like to prove that Rust is a fast language. The work that the compiler does is irrespective of the language that rustc is written in.