After some time investigating our builds using the macos.m1.medium.gen1 resource class and also inspecting local builds I found that even for a trivial Xcode project the test suite never launches.
While attempting to debug via SSH any operations through xcrun simctl spawn take at least several seconds to return, if more than one simulator is booted this can be as long as a minute.
The workaround for now seems to be to use macos.m1.large.gen1, however as noted by others runtime here is about double what I observed on medium resources with Xcode 14.
The Xcode 15 release notes mention at least the slow simulator launch performance as a known issue, however it is unclear to me which resource is the limiting factor here since neither CPU or RAM consumption seemed unusual.
- Executing Unit/UI tests from Xcode on the iOS Simulator takes an extended time to launch on first run of the suite. (115187363) (110330776) (FB12237092)