Aha! You haven't hit the LOC barrier that starts to make swift & xcode/source kit act like bsaul described. At around 100kloc you will start to get that experience with swift. While an equivalent 100-200kloc line app written in objective c will work quite fine with xcode. You'll start noticing some degradation as you get to 60-70kloc. You also have a simple module structure, which makes things better.

You can see it happen pretty plainly with a simple codegen script creating a bunch of dummy code up to X lines of code.