Be thankful you don't have to interact with tsc or eslint on a daily basis.
kotlinc is way slower than javac but damn, it's still pretty fast compared to what else is out there.
I use both on a daily basis. TSC is much faster than kotlinc for me. I'll give you that eslint is slow too.
I've recently been profiling kotlinc and there are files in our codebase that compile at 5loc/s!