I'm a huge fan of ninja and there are plenty of resources on the internet documenting how fast it is and why (it delineates a clear separation of responsibilities between IDE and build system).
https://aosabook.org/en/posa/ninja.html
I personally find myself wondering if, rather than the Swift Package manager migrating to the full Swift-Build juggernaut it shouldn't be supporting generating build.ninja files instead. Perhaps even Xcode could also be doing this in the long run rather than generating proprietary "PIF" format?