It's true, no April fools. You can make your Browser tests run much quicker. How? By deleting them!
You will of course need to add a corresponding Kernel test - and that's the trick. Kernel tests run much faster than Browser tests.
But Browser tests make requests to the test site using an internal web browser, I hear you say, whereas Kernel tests make API calls directly. Kernel tests have their uses for testing APIs, but Browser tests are needed to test actual HTML output.
Aha! Kernel tests can now make HTTP requests.
This is subject to a number of caveats and limitations: there is no session, and forms can't be submitted. And functionality such as a current user, blocks on the page, and page caching will need additional setup.
And more generally, with Kernel tests, modules are enabled but not installed: you need to handle things like entity schemas, database tables, and install config yourself in the test. The benefit though is that you only set up the parts of the module that you need for your test.
So not all Browser tests are suitable for conversion. But a lot of them are. We're already working on converting tests in core, and as this feature has been backported to Drupal core 11.x, contrib modules can make use of it too.
The benefits to conversion are tests that run faster, so less time developing and less time waiting for CI pipelines to run, and a lower energy footprint and lower costs for drupal.org. And they're easier to debug too.
And if you haven't yet written any tests for your module, now is an excellent time to start!
Do you need help with writing PHPUnit tests, or getting started with test-driven development? I'm available for hire - contact me!