On the Laravel News blog, Tim MacDonald wrote a nice collection of tips on how to make PHPUnit tests run faster.

Having a fast test suite can be just as important as having a fast application. As a developer, getting feedback quickly about the state of your code allows for a much quicker development turnaround. Here we are going to run through some tips you can implement today to make your tests run faster.

https://laravel-news.com/tips-to-speed-up-phpunit-tests