I got a request to share my project (15k LOC) with the compiler team because they had no larger projects to test on. This was less than a month ago. Draw your own conclusions on how much Swift has been used internally at Apple. Oh, and compile times for any change in that project was 50-60 seconds. That's a minute for changing a single character in one of the Swift files.

Since they don't seem to be scrambling to fix that problem, I can only assume that there's no urgency internally at Apple to fix it.