We run our Python tests in hundreds of environments really fast by using a combination of tools such as pytest, Flake8, black, mypy, Tox, GitHub Actions, and scripting to optimize the test suite's performance. We initially ran the tests sequentially, which took 40 minutes, but then implemented changes that allowed us to run the tests in parallel, reducing the time to around 10 minutes. These improvements were achieved by splitting up the test suite into smaller frameworks, using Tox's `--parallel` command, and creating separate GitHub Actions workflows for each framework. Additionally, we removed unused tools from our workflow and started logging slow tests to identify areas for further optimization.