https://www.jessesquires.com/blog/measuring-compile-times-xcode9/

Measuring Swift compile times in Xcode 9

The Swift type-checker remains a performance bottleneck for compile times, though it has improved tremendously over the past two years. You could even say the type-checker has gone from being drunk to sober. To help users debug these issues, awhi...

12:15 PM

これで設定した閾値以上コンパイル時間かかっている箇所に警告が出るようになるはずです。

12:18 PM

コマンドラインからのビルドで、もっと網羅的に見たいなら、 https://github.com/apple/swift/blob/master/docs/CompilerPerformance.md#how-to-diagnose-compilation-performance-problems の -Xfrontend -debug-time-function-bodies や -Xfrontend -debug-time-expression-type-checking が使えます。

apple/swift

swift - The Swift Programming Language