Mix test startup is slow

Having the same issue as OP, except I’m not using Quantum. I’ve run :fprof as described here, but not getting much:

Looks like a lot of time spent waiting and starting genservers? Would appreciate any guidance on profiling this further, it’s seriously affecting my change->test dev loop.

I’m on Mac OS 12.0.1, elixir 1.11.4, erlang 23.3.

PS: there was a warning about reviving this topic, but no guidance as to whether that’s acceptable or not. I’m pretty sure the topic applies, so just went ahead with it.