Scala's compile times (along with other aspects of its development experience) are among my biggest annoyances with the language. It just seems like it should be way better than it is for such an intellectually advanced language.

I've been investing a lot of time in learning Scala because I think that it's at the head of the vanguard of a software engineering revolution, but with some of its ergonomic issues, I can't help thinking it's eventually going to lose out to something that's more elegant from a design standpoint and has better tooling.

It's basically equivalent to Scala for the compilation itself (no noticeable difference). But the browser refresh in dev mode can take up to 5 seconds (or down to under 1 sec, depends on the machine). There is a tool that helps with this by using clever tricks to refresh the browser without reparsing the standard lib: https://github.com/lihaoyi/scala-js-workbench