If you find yourself having a bunch of slow tests that don't need to execute every time you run the tests, take a look at PHPUnit's defaultTestSuite setting. TJ Miller explains it in a blog post he wrote last year.

To avoid running the interactive test suite with the rest of my tests, manually or via a CI job, I had to explicitly include all the other suites using phpunit --testsuite Api,Feature,Unit. This felt a bit grim and I would rather exclude just that one suite. So I did some digging and found the defaultTestSuite configuration for phpunit.