Parallelization needs more work for it to be really solid, but it seems to work for many simple tests. Relatedly, I did some benchmarking: https://github.com/lambdaisland/kaocha/pull/234#issuecomment-906959800.

If you have a test suite that would benefit from parallelization, I'd be interested to hear from you. What tests do you have? When it's a little more polished, would you be willing to test or benchmark parallelized test runs? It's easy enough to document how to turn on parallelized test run (set :parallel to true in tests.edn), but I think for this feature to be useful, the documentation will also have to include information on what kinds of tests benefit from it and what kinds of common tests aren't thread-safe. I'm hoping to hear from Kaocha users to help research this part of the documentation. Having real-world tests will also let me determine whether parallelizing at the namespace level is enough (current approach) or if we need to consider working at the test level.