The Rust ecosystem is getting slower faster than the compiler is getting faster. Libraries grow to add features, they add dependencies. Individually the growth is not so bad, and justified by features or wider platform support. But they add up, and especially dependencies adding dependencies act as a multiplier.

I started writing a post about this many years ago, but never finished it. I took a few slow-changing projects of mine that had a pinned Rust compiler, and then updated both the compiler and dependencies to the latest versions. Invariably, everything got slower to compile, even though the compiler update in isolation made things faster!