Here’s two quick settings you can change on Xcode, one’s pretty minor, but the second one could be a big time saver. This first one will show you the build time on the activity bar, to enable it just enter this into the Terminal.

defaults write ShowBuildOperationDuration -bool true

To disable it, just change true to false.

The second one is to enable Xcode to use all cores available to your machine.

defaults write IDEBuildOperationMaxNumberOfConcurrentCompileTasks `sysctl -n hw.ncpu` 

That last part specifies how many cores your machine has, for example, in my 15” Retina MacBook Pro [quad core i7], since it has hyperthreading it, it returns 8.

Thanks to @merowing_ for both of these tips!