Currently, our test suite is not that large and it takes around 6-8 minutes to complete, but with testing every minute counts (testing is generally not that fun and a slow test suite just makes it more painful).
We have a two types of tests:
- Twisted tests - this tests runs asynchronously and finish pretty fast so they are generally not that problematic - Django tests - Django tests don't run in parallel so they are pretty slow. Recently, I was playing around with the Django test runner and I have made some modification to it to run the tests in parallel. Now the Django tests finish around 50% faster.
The only problem with this solution is that it is a "hack" and it requires some modifications to the Django core (I guess I should play more with the nose parallel test runner).
We also use some other "tricks" which make tests run faster - for example, MySQL data directory on a test server is stored on a ram disk.