How bad are the compile times? My understanding is that the compile times are currently bad, and they can't be improved without fundamental changes to the lang/type system.
For our API server https://api.heiioncall.com/ , on my Ryzen 5950X, with a warm CRYSTAL_CACHE_DIR ("where Crystal caches partial compilation results for faster subsequent builds"), making a one-line change:
Without --release:
6.11user 2.37system 0:08.19elapsed 103%CPU (0avgtext+0avgdata 590844maxresident)k
With --release: 76.54user 5.49system 1:25.16elapsed 96%CPU (0avgtext+0avgdata 696876maxresident)k
So let's call it about 9 seconds while developing, or 90 seconds for a CI build with full release optimizations.