Not that I've tried ReScript but it advertises fast builds, which the (sample size of one) large scala codebase I've worked on was really slow to compile.
Yes, it pretty much depends on what and how you're trying to compile. Incremental complication helps a lot, as does keeping sbt shell open and not restarting sbt each time.
In other news: now, there's scala-cli for smaller projects — https://scala-cli.virtuslab.org/docs/guides/scala-js