I haven’t used Rust on any significantly sized project. Could you elaborate? Is it only slow to compile release builds?

It is generally slower to compile than we would like. We have and will continue to spend a lot of engineering time improving it. It is often one of the largest feature requests from the community.

I started learning rust as a quarantine project, and my <5000 line project takes ~10 seconds to do an incremental development build and 1-2 seconds to typecheck

I work with a ~10k line project and it takes 60s to incrementally compile on a Ryen 3990X. Rust is great, but the compile times do need to improve :-)

What do you mean by "incrementally compile"? an addition of a single line of code results in a 60s build? never experienced anything like that, only the first compile is slow for me.

Incremental compilation results are subjective. If you just changed the file with "main" in it and there was nothing else in there, I'd expect it to be faster than changing a file at the bottom of the dependency tree as you then have to recompile a lot more.

Perhaps they're changing some fundamentals of the codebase and (unsurprisingly) the compiler seems slower than you might expect.

Yes, unfortunately, most of my work is on low-level shared libraries and it often wants to rebuild everything.