> That seems high to me. Where does that come from?

it is high (and i agree too high imo), but many apps utilize a lot of 3rd party libraries that take a loooong time to compile (just off the top of my head, various "reactive" frameworks, realm, firebase related libs etc)

you might ask why not deliver binary libs to cut down the time, well that used to be easy with obj-c/c dylibs but swift doesnt have a stable abi outside of apple libs, so every new swift update requires recompilation and swift package manager doesnt have much in the way of caching binaries for dependencies in a ci afaik