SpeedTraphelps**identifyslowtests**butcannotexplain**why**thosetestsareslow.Forthatconsiderusing[Blackfire.io](https://blackfire.io) to profile the test suite, or another PHPUnit listener [PHPUnit\_Listener\_XHProf](https://github.com/sebastianbergmann/phpunit-testlistener-xhprof), to specifically identify slow code.
[SymfonyFramework](https://symfony.com/) comes with package [symfony/phpunit-bridge](https://packagist.org/packages/symfony/phpunit-bridge) that installs its own version of PHPUnit and **ignores** what is defined in your project's composer.json or composer.lock file. See the PHPUnit versions it installs with command `ls vendor/bin/.phpunit/`