There have been quite a few recent threads on speeding up compile time using various mechanisms, and various problems people have had.
https://users.rust-lang.org/t/compile-time-efficiency-of-c-templates-vs-rust-generics/103532
https://users.rust-lang.org/t/compile-time-help/103397
https://users.rust-lang.org/t/is-rust-compile-time-really-that-slow/102863
https://users.rust-lang.org/t/extreme-long-compilation-time/101885
https://users.rust-lang.org/t/rust-compile-times-and-dependency-graphs/101209
https://users.rust-lang.org/t/compile-time-issues-after-merging-microservices/98484