`cargo check` that does all the parsing, type system checks, and lifetime analysis is pretty fast compared to builds. Rust compilation time spends most time in

`cargo check` that does all the parsing, type system checks, and lifetime analysis is pretty fast compared to builds. Rust compilation time spends most time in LLVM, due to verbosity of the IR it outputs, and during linking, due to absurd amount of debug info and objects to link. When cargo check isn't fast, it's usually due to build scripts and procedural macros, which are slow due to being compiled binaries, so LLVM, linking, and running of an unoptimized ton of code blocks type checking.