January 18, 2016 I had a problem. The new iOS application that I’m working on – written 100% in Swift – was noticeably taking much longer to compile than should, given its size (~200 files). More concerning, it was suddenly a lot slower than only a couple of weeks prior. I needed to get to the root of the problem as soon as possible, before it got any worse. The first step was to add -Xfrontend -d