It’s not just Rust. Practically every compiler based on LLVM is slow. Swift, Zig, Clang.

The Go compiler being written from scratch based on the Plan9 C compiler is a huge advantage.

Minor correction: Go compiler used to be a modification of Plan9 C compiler, then a Go port of that modification but then it was completely rewritten as a SSA-based compiler so today it has almost nothing to do with the original Plan9 code.

I will chime in to day that rust is also building a alternative to the LLVM backend in the form of cranelift : https://github.com/rust-lang/rustc_codegen_cranelift

Zig is moving away from LLVM. Its already has its own backend targeting debug builds for x86 and arm. ReleaseFast and ReleaseSmall is an entire different beast, but its going to be tackled eventually.

I wonder why we do not split up compilation more - especially for web developer. Rust does this a little with "check", C with "-O".

I want fast compilation for my dev cycle or for unit tests, I want slow compilation with optimizations, escape analysis, correctness etc. for production (the distinction between a compiler and linter is also not clear, some compiles do what linters do in other languages).

We do, you have profile configuration for dev or for release

You can get pretty big differences in terms of compile speed / binary size

Giving up entirely on the compile time of "performance" builds can be bad too though, e.g. for people writing games, audio software, etc.

Only if you need to test the full game. If you can unit test algorithms and learn something then fast builds matter.