Compile times in Rust are partly the amount of analysis that occurs, partly that it uses LLVM which is optimized for creating fast code at runtime but not necessarily fast-compiling code, and partly the fact that the Rust compiler is inefficient and does the same work twice or recompiles things it doesn’t need to.

But you can speed things up a lot by organizing your project into separate crates (which are compiled in parallel) and tweaking compiler flags. I speed up a large project by 7x this way.

Also, if you’re using fat LTO in release builds, switch to thin. It’s almost as fast at runtime and much much faster to compile.