As my project has grown over the past year, so have its build times. Over the last few months it\'s gone from 4 minutes to around 7 (time includes GitHub pull, unit tests, etc).
Here's an article about benchmarking/speeding up compilation time - swift-profiling.
In case it goes dead here is the tldr:
xcodebuild -workspace App.xcworkspace -scheme App clean build OTHER_SWIFT_FLAGS="-Xfrontend -debug-time-function-bodies" | grep .[0-9]ms | grep -v ^0.[0-9]ms | sort -nr > culprits.txt
You can just run that or add the following flags to your build under the other-swift-flags in build settings:
-Xfrontend -warn-long-function-bodies=100
This will show you which lines are slowing down your compile time.