[maxmcd]

Tests are usually embarrassingly parallel. Instead of creating one test db (app_test) create many (app_test_0, app_test_1, ...). Run tests in many threads/processes, db per thread.

This works in a lot of cases. In some cases this might not address your bottleneck.

Also someone should write a real, performant, in-memory postgres storage driver. Then we can all be happy (with pg at least).