> very slow compilation times

That isn't always the case. Slow compilations are usually because of procedural macros and/or heavy use of generics. And even then compile times are often comparable to languages like typescript and scala.

Compared to C, rust compiles much slower. This might not matter on performant systems, but when resources are constrained you definitely notice it. And if the whole world is rewritten in Rust, this will have a non-significant impact on the total build time of a bunch of projects.

typescript transpilation to js is nearly instant, it's not comparable