Jest is full of unneeded magic (= complexity), whereas node:test is straightforward and has a better design. Highly recommended. You can turn off process isolation for extra speedup!
Without process isolation we got 6x speedup vs. jest! But it is difficult to ensure a clean slate between our test suites (~40 suites which all use a test DB)
We are also using some helpers to mock, e.g https://github.com/marchaos/jest-mock-extended - its such helper libraries im concerned about.
We're working with a relational db, and we're DELETE FROM all tables that we use at the beginning of each test. That's fast enough so far. Process isolation doesn't help you with state in out-of-process dependencies anyway.
AFAIK JUnit and other test runners don't do any process isolation for unit tests. Why is JavaScript so different?
If I could just make some rules that all engineers would follow exactly, I'd simply make a rule "write no bugs" and then I wouldn't need a test framework at all.