Did you create your own dialect of C++ along the way? I see co_try$(...) and co_trya$(...) whose definitions I can't find, and I assume they're macros that work either with or without coroutines... did you measure the performance overhead with coroutines?

Theses macros are defined in our framework, the coroutine code is not that hot so we didn't measure the overhead

https://github.com/skift-org/karm